Sylvia Tilly

Captain Sylvia Tilly was an antagonist introduced in the Star Trek: Discovery episode Despite Yourself.

Thus far she, aside from an image in a personnel file she has not actually appeared in licensed media. The image of Tilly from her file was portrayed by Mary Wiseman, who portrays her primary universe counterpart. Unlike her counterpart, Tilly's hair was colored blonde and she wore it straight.

An officer in the Imperial Starfleet of the Terran Empire, Tilly began her career at the Imperial Starfleet Academy, where she graduated with distinction. She also participated in actions that led to Tilly being known as The Slayer of Sorna Prime and The Witch of Wurna Minor.

Tilly later became the Captain of the Crossfield class starship ISS Discovery after murdering the ship's previous Captain. Her actions as Captain further led to her becoming known as Captain Killy.

During her career Tilly was decorated for valor, for having 50 kills, and being a Master of Poisons. Her prime universe counterpart was greatly disturbed over Tilly, saying that the woman was nothing like her, that she was a twisted version of everything she aspired to, and that she would have nightmares about her counterpart.