1. Viola: She is the daughter of Sebastian Messaline. She has survived a ship wreck but thinks that has lost her brother. She worries about her brother a lot.
'Viola: O my poor brother! And so perchance may he be.'
However, she forgets about her grief for her brother as she finds out that Orsino, duke of Illyria, is a bachelor. She begins to like him and wants to marry him.
'Viola: Orsino! He was a bachelor then.'
She disguises as a eunuch and serves Duke Orsino and is known as Cesario. She gets the duty to woo Countess Olivia for Orsino. While she is doing her job, Countess Olivia likes Viola. Viola gets to know about it and hopes time will untangle this.
'Viola: Fortune forbid my outside have not charmed her!'
2. Olivia: She is the countess. Her father and brother have died recently. She also loved her brother and is in the same situation as Viola.
She mourns for her brother everyday for seven years. That worries everybody in the house. Orsino loves her or at least pretends to love her but Olivia doesn't love him at all.
'Olivia: A gracious person. But yet I cannot love him.'
Viola comes to woo Olivia for her master. Olivia finds Viola very interesting and attractive. Olivia removes her veil for the first time after her brother's death just for Viola.
'Olivia: Even so quickly may one catch the plague?'
3. Toby: Sir Toby is a comic character. He is Olivia's uncle. He is a great juggler with words, even when he's been drinking. He is almost always drunk.
'Sir Toby: Confine? I'll confine myself no finer than I am; these clothes are good enough to drink in...'
He wants his niece to marry, Sir Andrew, whom everybody thinks that...