Captain Jack Absolute is a practical young man who is dominated by his father and is in love with Lydia. He takes on the identity of Ensign Beverly in trying to win Lydia's attentions.
Sir Anthony Absolute, a domineering personality, is Captain Jack's father. He has engineered his son's military career, and ruthlessly tries to control his choice of a spouse as well.
Lydia Languish is Captain Jack's love interest, a lovely young lady who lives in a fantasy world of romantic novels. She longs to marry below her station because it is a "deliciously forbidden act", and will horrify her proper Aunt.
Mrs. Malaprop is Lydia's Aunt, a proper lady who comically tries and fails to adhere to the highest levels of sophistication.
Fag is Captain Jack's servant.
Bob Acres is a "country squire" who has been trying unsuccessfully to win Lydia's heart.
David is Bob Acres's noble servant.
Sir Lucius O'Trigger is an ancient, comical Irishman who also has been trying to woo Lydia.
Julia Melville, who is being courted by Faulkland, is the ideal female character.
Lucy is Julia's manipulative maid.
Faulkland, a fretful, mercurial man, is pursuing Julia, and plays a foil for Captain Jack.
Thomas is Sir Anthony Absolute's coachman.
A complete and detailed summary of characters can be found at the enotes link below.