I should be writing symphonies. Not tagging along after some headstrong teenager!
~ Sebastian's catchphrase
Horatio Thelonious Ignacious Crustaceous Sebastian, simply known as Sebastian or Sebastian the Crab, is a red Jamaican crab and the tritagonist in Disney's 28th full-length animated feature film The Little Mermaid. He is the "distinguished" court composer for King Triton, and is regularly tasked with watching over his youngest daughter, Princess Ariel.
Sebastian is the attaché of King Triton. He and King Triton keep an eye out for any music in Atlantica after Triton banned it following the death of his wife Queen Athena. Though he agrees with King Triton, Sebastian usually is seen playing music in the Catfish Club Band. He and the band members are arrested by the king's guards in jail. Being arrested, he and the band members start a prison riot and escape to bring music back to Atlantica. He and Ariel's friends stand up against Marina Del Rey. Sebastian later listens to King Triton's misunderstanding and becomes the royal court composer after Triton lifts the ban on music.
The Little Mermaid
After the prequel, Sebastian is presented along with King Triton. He is forced to keep a watch on Ariel. Sebastian has heard about Ariel falling in love with Prince Eric. Later, he convinces Ariel that the human world is too dangerous for her, so it is better to stay under the sea. After King Triton destroys Ariel's treasures, Sebastian is remorseful as he had told Triton about Ariel being in love with Eric. Sebastian disapproves of Ariel going with Flotsam and Jetsam to see the sea witch Ursula.
Sebastian later plays another signature song about Eric and Ariel falling in love as humans. He dislikes marine animals which are cooked, so he avoids Chef Louis. During the wedding of Eric and Vanessa (really Ursula in disguise), Sebastian and the other animals disrupt the wedding and Ursula is discovered. Sebastian is later seen during the wedding of Prince Eric and Princess Ariel.
The Little Mermaid II: Return to the Sea
Sebastian appears as one of the two main deuteragonists of The Little Mermaid II: Return to the Sea. Sebastian is tasked by King Triton to watch over Ariel's daughter, Princess Melody, repeating his role from the original film (much to Sebastian's chagrin). Sebastian disapproves of Melody's obsession over the sea, knowing the dangers that lie within them (namely Ursula's sister Morgana, who seeks to unleash her wrath upon Melody and her family), but the headstrong princess fails to listen, finding herself completely captivited by the world of the ocean.
One evening, during a ball, Sebastian accidentally finds himself in the ballroom, amongst the crowd of royals, and more importantly, the psychotic Chef Louis, who tries to murder the crab out of spite. Sebastian manages to escape, but unintentionally embarrasses Melody in the process, reinforcing her fear of being an outcast amongst her fellow royals. Later that night, Sebastian tries to cheer up the child, but it results in her leaving into the sea. Sebastian quickly informs Ariel and Eric, and a search breaks through. King Triton is informed of this and, after turning Ariel back into a mermaid, the team takes the search into the waters. Eventually, the family finds themselves battling Morgana at the sea witch's lair. She soon meets her defeat at the hands of Melody, and with her out of the way, peace can be restored between land and sea.
Sebastian appears in almost every episode of the prequel television series. Sebastian is shown as being a good friend of Ariel and Flounder. He is sometimes strict and often critical of Ariel's adventurous ways, but often ends up going on her adventures with her. Throughout the series, Sebastian's character is further developed via dialogue and entire episodes dedicated to him. In the episode "Tail of Two Crabs", Sebastian has a rivalry with a crab named Zeus, and they both try to one-up the other. According to dialogue in this episode, Sebastian was born in Jamaica and went to Music Academy in Trinidad prior to joining King Triton's staff as his assistant; in "Eel-Ectric City" he also reveals he had the stage name "Dizzy Crustace" (krust-AY-she).
Sebastain is also the main protagonist of his segments from the series Marsupilami.
Sebastian made an appearance in three titles of the Kingdom Hearts series of video games, voiced by Kevin Michael Richardson in the English version and Kōichi Yamadera in the Japanese version.
In the Broadway stage musical adaption, Sebastian's role is similar but modified from that in the film. He is not in the scene where Ariel saves Prince Eric, and his song "Under the Sea" is moved to after Triton destroys Ariel's treasures instead of before it. Sebastian also provides vocals for the new song "If Only". The role was originated by Tituss Burgess, and has also been performed by Alan Mingo Jr. and Rodgelio Douglas Jr..
Originally, Sebastian was to have an English accent.
Eddie Murphy, Danny Glover, the late Robin Williams, John Goodman, Nathan Lane, Ving Rhames, Keith David, Ziggy Marley, Frank McRae, Isaac Hayes, Tim Allen, the late Bob Hoskins, Bruce Campbell, Eugene Levy, and Daniel Stern were considered for the role of Sebastian.