Orsino The Duke of Illyria and its ruler. At the opening of the comedy, he is desperately in love with Lady Olivia, who spurns his romantic overtures in spite of the fact that he is a perfect and ideal gentleman.
Viola/Cesario After being shipwrecked, she disguises herself as a young boy, takes the name of Cesario, and attains a position in Duke Orsino's household because of her wit and charm. As a boy, she is then used as an emissary from the duke to court Lady Olivia. Her twin brother, Sebastian, looks exactly like her.
Lady Olivia She is a rich countess who, at first, plans to mourn her brother's recent death for seven years, but when she meets the emissary from Duke Orsino (Viola disguised as a boy), she immediately falls in love with the youth.
Sebastian The twin brother to Viola who is mistaken for Cesario when he (Sebastian) arrives in town. He meets Olivia and enters immediately into a marriage with her.
Antonio A sea captain who aids and protects Sebastian; his pleas for help are ignored by Viola, who in her disguise looks exactly like her twin brother.
Sir Toby Belch Lady Olivia's uncle who lives with her and who is given to constant drinking bouts; he delights in playing tricks on others.
Sir Andrew Aguecheek A skinny knight who is encouraged by Sir Toby to continue courting Lady Olivia because as long as he courts Lady Olivia, Sir Toby can gull him out of enough money to continue the nightly drinking bouts.
Malvolio Lady Olivia's steward who also has fantasies that Lady Olivia might someday marry him. He is opposed to Sir Toby's drinking bouts, and, thus, he becomes the object of one of Sir Toby's elaborate tricks.
Maria Lady Olivia's waiting woman; she is clever and arranges a superlative trick to be played on Malvolio.
Feste A clown, or "jester," in the employ of Lady Olivia; he has a marvelous way with words and with making a sentence "get up and walk away."
Fabian Another servant of some importance in Lady Olivia's house.
Valentine and Curio Two gentlemen who attend Duke Orsino.
A Sea Captain He appears in only one scene. He helps Viola with her disguise.