Molly Shannon has signed on to the Showtime half-hour comedy pilot “Big Deal,” Variety has learned.

She joins previously announced lead Vanessa Bayer in the pilot, in which Bayer plays a character who overcame childhood leukemia to achieve her lifelong dream of landing a job as a successful home shopping channel host. Shannon will star as Jackie, the charismatic, popular host at the network. Bayer’s character is inspired by her own life.

Like Bayer, Shannon is a “Saturday Night Live” alum. One of her signature characters, Mary Katherine Gallagher, led to Shannon starring in a standalone film titled “Superstar” in 1999. She was also nominated for an Emmy for her work on “SNL” in 2000, one of three Emmy nominations Shannon has netted throughout her career. She was also nominated for her work on “Enlightened” in 2013 and for “Will & Grace” in 2018. Her recent TV credits include the critically-acclaimed Comedy Central series “The Other Two” and the HBO comedy “Divorce.”

She is repped by UTA, Framework Entertainment, and Hansen Jacobson.

Bayer co-created “Big Deal” with Jeremy Beiler, with both also executive producing. Jessi Klein will serve as showrunner and executive producer. Michael Showalter is executive producing and directing. Showalter and Shannon previously worked together on the cult classic film “Wet Hot American Summer” and the subsequent Netflix shows “Wet Hot American Summer: First Day of Camp” and “Wet Hot American Summer: Ten Years Later.” Megan Ellison and Sue Naegle of Annapura will executive producing along with Jordana Mollick of Semi-Formal. Showtime will produce.