Twenty-two-year-old Dianna Agron hasn't been acting for very long, but she has already has a handful of hit television show appearances under her belt, most notably on "Heroes" and "Veronica Mars." Agron plays in "Glee" a Cheerio (that's cheerleader in McKinley speak) who's devoutly religious, but is a true mean girl through and through.

Earlier this decade, Jayma Mays graduated from Radford University with a degree in performing arts. Since then, the adorable redhead's career has skyrocketed, and for the past five years, she has made numerous appearances in plenty of high-profile shows including: "Six Feet Under," "Entourage," "How I Met Your Mother," "Heroes" (as Masi Oka's love interest, Charlie), and "Ugly Betty" (as Betty nemesis, who also happened to be named Charlie). This go-round finds Jayma back in high school as Emma Pillsbury, a teacher/germaphobe who agrees to help restore the club in exchange for spending an unhealthy amount of time with her married co-worker/Glee Club sponsor, Will Schuester. Glee

Jack Coleman stars as H.R.G. in Heroes.

Ali Larter stars as Niki Sanders/Jessica in Heroes.