Deadline has reported that Katie Aselton has joined the expanding cast of FX's "Legion," a drama series based on the X-Men character of the same name. No information about Aselton's character has been revealed other than a name: Amy.

Aselton previous starred in the FX (and later FXX) comedy series "The League." She has also had recurring roles on Hulu's "Casual" and HBO's "Togetherness."

The pilot comes from "Fargo" showrunner Noah Hawley and will star "Downton Abbey's" Dan Stevens as David Haller, the son of Charles Xavier and a man with mental illness and haunted by voices in his head. "Legion" will also star Aubrey Plaza, Jean Smart, Jeremie Harris, Amber Midthunder and Rachel Keller.

"Legion" is in development at cable network FX, with Hawley on board as a producer. According to the official description, "Since he was a teenager, David has struggled with mental illness. Diagnosed as schizophrenic, David has been in and out of psychiatric hospitals for years. But after a strange encounter with a fellow patient, he's confronted with the possibility that the voices he hears and the visions he sees might be real." Production on the "Legion" pilot will begin in March.