Gemma Martindale
Main aliases: Sybil Vane
Species: Human
Place of origin: England
First seen in: Ghosts of Christmas Past
Main actor: Rebecca Newman

Gemma Martindale is the illegitimate daughter of Alan Campbell. She poses as Dorian's long lost first love, Sibyl Vane, to lure him into an elaborate revenge plot concocted by her father.

When the plot is foiled by Sherlock Holmes and Dorian working together she is arrested with her father and presumably hanged for the murder of Lord Henry Wotton alongside him.