Olivia is a character in William Shakespeare's play TwelfthNight. She is in mourning because of the recent death of herbrother. She is a wealthy woman with no parents or siblings, whosecousin, Sir Toby Belch, lives in her house. She is unmarried andthe Duke Orsino wants to marry her. So does a rich but foolishknight, Sir Andrew Aguecheek. But she will not entertain the ideaof marrying anyone.