Felicia Day was born in Huntsville, Alabama, and grew up all over the South, part of a military family. She was home-schooled her whole life and started participating in theatrical productions when she was very young, as an actor and a dancer. She attended college at the age of 16, and subsequently graduated as Valedictorian of her class, completing degrees in Mathematics and Violin Performance at the University of Texas at Austin. Shortly thereafter, she moved to Los Angeles to pursue a career in acting, her dream.

As an actress, she has appeared on TV shows such as House, Strong Medicine, and Monk, and films such as Bring it on Again and the Emmy award-winning Warm Springs. She had a recurring role as Vi in the last season of Buffy the Vampire Slayer and can be soon seen in a four-episode arc on the new ABC Family sitcom Roommates.

Currently, Felicia is most widely known for her work in web video, and co-starred in Joss Whedon's Internet musical Dr. Horrible's Sing-a-long Blog, voted the Best TV of 2008 by Time Magazine, Entertainment Weekly, and People Magazine, just to name a few. She also can be seen in the web series The Guild, which she created, writes, and stars in. The Guild was the winner of the YouTube, Yahoo, and SXSW Best Web Series Awards for 2008 and for the first season alone collected over 11 million hits web-wide. Recently, in a ground-breaking deal, The Guild partnered with Xbox to produce and release Season 2 on the Xbox Marketplace as well as other Microsoft distribution platforms. Day retained complete creative rights and control of the show.

In her downtime, Felicia's hobbies include video games, reading (particularly science fiction/fantasy), writing, and performing sketch comedy and improv comedy.