Who is Sybil Vane from The Picture of Dorian Gray and what is their importance?

Sybil is a young actress, who performs Shakepeare in London. Unfortunately, he performances are only seen in the not so affluent theatres of London. Sybil and Dorian fall in love, but Dorian quickly ends their relationship after Sybil gives an unsatisfactory performance. Sybil, in turn, takes her own life.