Which actress played Cindy, The Mother's roommate, in Girls Versus Suits?

Rachel Bilson played Cindy, the Mother's roommate, in “Girls Versus Suits.”

Cindy is a Ph.D. student whom Ted meets after encountering her outside his university class. Ted begins dating her, but Cindy is frustrated because her roommate repeatedly attracts the attention of Cindy's dates. The roommate is eventually revealed to be Tracy McConnell, the woman who will become the Mother.

The episode originally aired on January 11, 2010, as the 100th episode of How I Met Your Mother and the 12th episode of season five. Bilson's casting was kept secret because Cindy's roommate is an important piece of the show's long-running mystery about the Mother.

Cindy later returns in additional episodes, including “Big Days.” Her storyline also establishes an important connection between Ted and Tracy before they ever meet: Ted leaves Cindy's apartment carrying the yellow umbrella, briefly glimpses Tracy, and unknowingly comes close to the future Mother. Jayma Mays, Abigail Spencer, and Sarah Chalke played other characters in the series, not Cindy.