(Portrayed by Mary Wiseman)

Ensign Sylvia Tilly started off her journey aboard the U.S.S. Discovery as a freshly minted Starfleet Academy cadet, all wide-eyed, good-natured, full of nervous excitement and humor, and determined to one day become a Starfleet captain. She took an immediate liking to her new roommate, Michael Burnham… the mutineer. The two women soon forged a friendship, with Burnham providing mentorship and Tilly helping Burnham relax, fit in and temper her Vulcan logic in favor of being more human. 

During the Federation-Klingon Empire war, Tilly grew up quickly. She witnessed death and destruction, but also mercy, love and heroism. Along the way, she worked closely with the initially cranky and impatient Lt. Stamets to develop the spore drive and she gained the respect of Saru. Tilly also surprised everyone, including herself, after the Discovery entered the Mirror Universe and she had to pretend to be the far tougher Mirror Tilly, better known as Captain Killy thanks to her exploits in pursuing rebels.

Once the war was won, Tilly was bestowed with the Starfleet Medal of Honor and promoted to ensign. As such, she is on the command track, with her goal of sitting in a captain’s chair – for real – in her sights.