Mamoru Chiba (地場 衛 Chiba Mamoru, Darien in the English dub) is Usagi Tsukino/Serena Tsukino/Sailor Moon's husband and the only major (human) male character in the Sailor Moon metaseries. He can transform into the rose throwing hero Tuxedo Mask in order to protect Sailor Moon; he is the reincarnation of Prince Endymion of Earth and in the 30th century he will be known as King Endymion. He is the future father of Chibiusa/Rini.
His name, just like the girls', carries a pun. His surname Chiba means local and contains the kanji 地 - chi which also appears in the word chikyuu meaning Earth and 場 - ba meaning place or location. His given name Mamoru 衛 means to protect. So the pun in his name is loosely Earth Protector or Local Protector.
He is voiced by Tohru Furuya in the original anime and in the English dub by Rino Romano, Toby Proctor and Vince Corazza. In the 2004 live action series, he is played by Shibue Jyoji then Mahou no Tsuki Kokoro: Minky Chibiusa. According to Naoko Takeuchi, he takes the place of Sailor Earth.
Tuxedo Mask or Tuxedo Kamen as he is known (while his name is pronouced Tuxedo Kamen in the original anime Japanese products are known to use both forms of his name and kamen is the Japanese word for mask) fights alongside and protects Sailor Moon and the other Sailor Soldiers.
Mamoru Chiba becomes the major romantic interest of Usagi Tsukino. The series often portrays him as stoic, steady and introverted. At a young age he lost his parents in a car crash. This blocked his childhood memories of his current lifetime and opened up the memories of his previous life as Prince Endymion. In the beginning of the series, dreams of Princess Serenity haunt Mamoru. Unaware of his dual-identity as Tuxedo Mask, he suffers painful headaches and visions whenever Usagi gets into trouble, and he transforms unknowingly into Tuxedo Mask. As Mamoru, he tries to piece together his strange dreams, and as Tuxedo Mask, he tries to remember his past and identity, while searching for Princess Serenity. Early in the manga he seeks the Silver Crystal in the belief that this will fully restore his memories. In the anime, he seeks it because Princess Serenity tells him to in a dream. Of all the characters, Mamoru gets brainwashed and captured the most throughout the series, probably because of his importance to Usagi.
Mamoru and Usagi become lovers during the series, although they hate each other initially. In the anime, Usagi and Mamoru don't know each other's shared histories, and don't know that they work together as Sailor Moon and Tuxedo Mask. In both the manga and anime he and Usagi feel antagonism towards each other and only develop romantic feelings later on. In the anime, Mamoru explains that when Usagi comes close, he doesn't know what comes over him, and for some reason he feels compelled to insult her. Their bantering sets up for a very passionate relationship. In the manga their feelings develop well before they discover their identities; in the anime such feelings emerge only shortly before the revelation of their true roles. Once they became a couple, they remain deeply devoted to each other and their love survives many trials. In the manga, they briefly show jealousy in Volume 8, Act 25. In the anime they break up in Episode 61 (55 in the English version) after King Endymion sends nightmares to Mamoru, making him believe if he stays with Usagi she will die. However, they re-unite in Episode 77. He is always addressed as Mamo-chan by Usagi throughout the series during this time period (Chibiusa also addresses him with this nickname later on). After dating for two years, Mamoru gives Usagi an engagement ring at an airport. Their wedding is shown at the very end of the manga. In the future, they become king and queen and have a child together whom they name, Small Lady, but is in the majority of the series known as Chibiusa.
The manga develops Mamoru more extensively, showing that the car-crash happened on his birthday, and it gives a glimpse of his parents. Mamoru also struggles with his identity and function throughout the manga, worrying first about his true nature, then later whether he gets in the way of the Sailor Soldiers. A fair amount of subtle characterization is made for Mamoru, and later extending his role within the manga as to who he is. He also is given the power of psychometry, which also showed up in the anime, but was not given a name. This manifests in his ability to see and read dreams (Such as Chibiusa's), heal people and monitor the status of the Earth. This was not fully developed until the Black Moon arc, and was used occasionally throughout the series. Mamoru also has his left ear pierced in the manga, a trait that does not carry over to his anime counterpart.
The anime tends not to develop Mamoru as much, but shows him as more social than his manga counterpart. He demonstrates interests in a variety of subjects and emerges as smart. The musical Kakyu Ouhi Kourin shows that he is aspiring to become a doctor. He also "dates" Rei Hino for a short time before the revelation of all the past-life identities, though he believes they are just friends.
Tuxedo Mask plays a significantly more important role in the manga than in the anime. In fact, many of Sailor Moon's transformations and final victories come as a result of her and Tuxedo Mask fusing their powers together. In the final battle against the Dark Kingdom, Queen Metaria absorbs Sailor Moon and Tuxedo Mask into her body. However, they succeed in combining their powers through the Silver Crystal and destroy Queen Metaria from within. Tuxedo Mask also combines his power into Super Sailor Moon's last item in the manga with the rest of the soldiers using the Golden Crystal. In the Infinity story arc, he combined his powers with Sailor Moon to create the next scepter.
The manga tends to show Mamoru as quiet, studious, mysterious and stoic. The student body of his high school often admires him for these qualities. The anime also tends to make him appear in every episode to save Sailor Moon's life. He did have a few attacks that resemble what would seem[original research?] like some of the attacks in the manga, but these are not given actual names within the anime.
The dub did not make many significant changes to Mamoru's character. He appears a little more extroverted than his original anime counterpart in the voicing. Darien was more likely to yell and get annoyed than Mamoru of the anime, who was often quiet and distant, even when he was annoyed. A line was also added to an episode in the dub that claimed Darien used to be a model, but this was never referred to again. The original line had Mamoru talking about the attractiveness of a girl's character being more important than physical beauty. It also invented karate as one of his hobbies, which was only mentioned in one episode and never mentioned in the original.
In the musicals, Mamoru protects Usagi and generally appears at her side. Several of his relationships change in different settings, however. For example, one musical reveals Queen Beryl as Mamoru's fiancé from his time as Prince of the Earth. Associating with the Moon Kingdom was against Earth law, and Endymion violated this law when he fell in love with Princess Serenity. In this version of events, Serenity and Endymion are outlaws (similar to Romeo and Juliet) who drive an otherwise innocent woman, Beryl, to evil by making her jealous. Sailor Pluto also reveals that she is in love with Endymion, though she has contented herself with watching from afar.
Another variation occurs in the Ryuusei Densetsu musical, when Galaxia does not kill Mamoru, leaving him able to fight alongside the Senshi. Mamoru typically gets very involved in Senshi battles, fighting alongside the Senshi as opposed to his anime rôle of throwing a rose and then letting Sailor Moon deliver the finishing blow.
Tuxedo Mask always gets his own song; these songs vary from musical to musical. One musical featured multiple songs as both the present Mamoru appeared as Tuxedo Mask and later King Endymion appeared in disguise as Space Knight to look out for Chibiusa.
The live-action version presents Mamoru as a much more silent, yet dedicated person. For example he stays loyal to Hina, his girlfriend (despite not loving her), on the basis of a promise they made as children. He searches for the Silver Crystal due to his amnesia: dreams told him that the magical object could restore his memories. To do this, he donned the Tuxedo Kamen disguise and became a thief, searching for the legendary crystal. Once he regained his memories of his past and present lives, he assumed his Endymion form to help the Senshi and tried his best to protect Usagi from the dangers of overusing the Silver Crystal. However, because of his dedication he is forced to join the Dark Kingdom or the Shitennou will be killed. He also joins to keep a promise with Usagi that they will not destroy the planet. Learning that the Silver Crystal made Metaria stronger every time Sailor Moon used it, Endymion took Metaria into his body before succumbing to its dark power. Now an evil parody of himself, Dark Prince Endymion, he almost killed Sailor Mercury when Sailor Moon was forced to kill him to stop Metaria. He was revived once Sailor Moon managed to finally control the Crystal's power and destroyed Metaria for good.
In the anime Tuxedo Mask throws red roses at his enemies, these seem to be magically sharp and can break objects. He also wields an extendable cane which he uses in combat. In the anime, he is also not aware that he is Tuxedo Mask until he figures out the meaning of his "Princess" dream in episode 26 (22 in the dub)  at which point he realizes his identity. He is killed by Sailor Galaxia after she captures his plane on the way to college in America, but later comes back to life when Galaxia is defeated.
In the manga he does not throw roses but in the Black Moon storyline (Sailor Moon R) he aquires an attack all of his own - Tuxedo La Smoking Bomber. He and Sailor Chibi Moon also a have combined attack called Pink Sugar Tuxedo Attack.
Prince Endymion is Mamoru's past life self, eons ago he was the crown prince of the Golden Kingdom of planet Earth who Princess Serenity of the Moon Kingdom was in love with, however this was forbidden love (in the anime because the two kingdoms were at war, in the manga because earthlings and moon people were forbidden from meeting) when the Dark Kingdom attacked the Moon Kingdom he stood against them and was killed, he was reborn on Earth in the late 20th Century.
When Queen Beryl brainwashes Mamoru and makes him evil in the latter half of the first season of the anime he forgets his love for the princess and that he was ever known as Mamoru Chiba and goes by Prince Endymion or Tuxedo Mask only (throwing a black rose rather than a red one).
The Moonlight Knight
When Mamoru is reborn and loses his memories at the end of the first season of Sailor Moon his desire to protect Usagi takes on coporeal form as the Moonlight Knight, he throws white roses and wields a sword. When the Doom Tree is defeated he merges with Mamoru and Mamoru's memories return.
In the 30th Century he takes on the name King Endymion and ascends to the throne alongside his now wife Neo-Queen Serenity and rules over the planet Earth and the Solar System with her. Together they have a princess who they name Usagi Small Lady Serenity who is better known as either Chibiusa or simply Small Lady.
In the anime
In the English anime, Mamoru is called Darien. His prince form is Prince Darien, but Tuxedo Mask and Moonlight Knight retain their Japanese/manga names.
Prince Darien was from Earth and fell in love with Princess Serena. Some of the guards mistook him for a spy, but Queen Serenity knew that he wasn't. When the Negaforce and Queen Beryl attacked, Beryl asked Darien to join her, but he refused, so she threatened to destroy him, and Serena as well, but they were all sealed inside the power of the Imperium Silver Crystal by Queen Serenity, who then sent them into the future, and Darien and all the Sailor Scouts, including Serena, to be reborn on Earth.
Darien often got into fights and arguments with Serena, and loves to annoy her and call her "meatballhead". As Tuxedo Mask, he would often show up to help her when she was at a disadvantage against a Negaverse monster, giving her the opportunity she needs to destroy them. When Zoycite began seeking rainbow crystals, Tuxedo Mask would often show up to take them.
Queen Beryl soon became interested in brainwashing Darien, and sent Zoycite to capture him by disguising herself as Sailor Moon and then stabbing him in the back, however, he escaped with help from Sailor Venus. Zoycite, aware that Darien was Tuxedo Mask, challenged him to a battle over the crystals. However, she double-crossed him, with Malachite taking the crystals, and he threw a rose at Zoycite to damage her face. Zoycite wanted revenge, despite the fact that Queen Beryl had ordered her to take him alive so she could turn him evil. Twice she tried to kill him; the first by shooting fire at him and Serena while they were in an elevator, forcing Serena to transform into Sailor Moon in front of Darien. Realizing Serena was Sailor Moon, Darien transformed into Tuxedo Mask, revealing his identity to her. However, Zoycite seriously injured him with an ice crystal. Beryl killed Zoycite as punishment.
From here, Beryl and the Negaforce brainwashed Darien to turn him evil. Though working for the Negaverse, Prince Darien often got into fights with Malachite, and even helped out the Sailor Scouts (as usual) against Malachite's monsters. In Episode 37, he was healed by Sailor Moon, but Malachite returned him to the Negaverse where Beryl brainwashed him again. He fought Sailor Moon a final time in Episode 40, and was unaffected by Moon Healing Activation, but Sailor Moon convinced him to touch the locket, which restored him to normal once again. Beryl threw a spike at them, but Darien through a rose at the spike to shatter it and injure Beryl. After Beryl was destroyed by Serena, both Darien and Serena's memories were erased, until Sailor Moon R.
Sailor Moon R
In Sailor Moon R, Darien initially does not regain his memories, but his desire to protect Serena takes the form of the Moonlight Knight. Serena suspects that he is Darien, but thinks that they cannot be the same when she sees Darien and the Moonlight Knight at the same time. Ann falls in love with him, similar to how Alan falls in love with Serena. At the end of the Doom Tree arc, the Moonlight Knight merges with Darien again and he regains his memories.
In the future, Prince Darien is the husband of Princess Serena, a.k.a. Neo Queen Serenity, and Rini is their daughter. As king, he appears to the Sailor Scouts as a hologram.
Sailor Moon R movie
After the accident that killed his parents and left him in the hospital, he meets a young alien, Fiore. Fiore has to leave Earth, so Mamoru gives him a rose, and is promised by Fiore to return with a flower for him. He does not remember Fiore when he comes back initnally. He is attacked by Fiore for protecting Sailor Moon, but is healed on Fiore's astroid. In the end, Fiore keeps his promise with a flower to revive Sailor Moon. It is also revealed that a young Usagi comforts Mamoru upon his learning that Fiore has to leave. The rose that Mamoru gave to Fiore was originally given to Mamoru from Usagi, celebrating the birth of Usagi's brother, Shingo.