Phylicia Rashad has been cast in the third season of “Empire,” joining the growing slate of prominent guest stars.

“The Cosby Show” alum will recur as Diana Dubois, a powerhouse from one of New York’s oldest and most prominent African-American families, and the on-screen mother of Taye Diggs, who will portray an ambitious city councilman, Angelo Dubois. Diana (Rashad) has her sights set on higher office for her only son and she’ll stop at nothing to groom him. Her interactions with Cookie (Taraji P. Henson), Lucious (Terrence Howard) and the rest of the Lyon clan will lay bare the stark class divides that can exist, even within the black community.

Rashad joins other previously announced “Empire” guest stars, including Mariah Carey, Sierra McClain, French Montana and Birdman.

Rashad famously starred on “The Cosby Show” as Bill Cosby’s TV wife, Clair Huxtable. In more recent years, she had had television roles on NBC’s short-lived “Do No Harm,” USA Network’s “Psych” and Lifetime’s “Steel Magnolias.”

“Empire” returns to Fox on Sept. 21 at 9 p.m.