The upcoming “Yellowstone” spinoff at CBS is rounding out its main cast.

“Y: Marshals,” which will see Luke Grimes reprise the role of Kayce Dutton, has added seven new cast members. Those include fellow “Yellowstone” alums Gil Birmingham, Mo Brings Plenty, and Brecken Merrill. The three will reprise their roles as Thomas Rainwater, Mo, and Tate Dutton respectively.

The official logline states:

“With the Yellowstone Ranch behind him, Kayce Dutton (Grimes) joins an elite unit of U.S. Marshals, combining his skills as a cowboy and Navy SEAL to bring range justice to Montana, where he and his teammates must balance family, duty and the high psychological cost that comes with serving as the last line of defense in the region’s war on violence.”

The new series regulars include: Arielle Kebbel (“Rescue: Hi-Surf,” “Ballers) as Belle, Ash Santos (“Pulse,” “Mayor of Kingstown”) as Andrea, and Tatanka Means (“Killers of the Flower Moon,” “Reservation Dogs”) as Miles. All three will play members of the U.S. Marshals. In addition, Brett Cullen (“Apollo 13,” “Joker”) will appear in the recurring role of Harry Gifford, the head of the U.S. Marshals in Montana. It was previously announced that Logan Marshall-Green would play Pete Calvin, a friend from Kayce’s time in the military.

Kebbel is repped by Independent Artists Group, Untitled Entertainment and Hansen Jacobson. Santos is repped by M88, Gersh, Platform Public Relations and Myman Greenspan. Cullen is repped by Innovative Artists and Lovett Management. Means is repped by Amsel, Eisenstadt, Frazier & Hinojosa Inc. and Authentic Talent and Literary Management. Birmingham is repped by Amsel, Eisenstadt, Frazier & Hinojosa Inc. Merrill is repped by Industry Entertainment, Paloma Model & Talent, and Bloch Law.

“Y: Marshals” was ordered to series at CBS in May for the 2025-2026 broadcast season. The series is slated to debut at midseason. The initial episode is being written by Spencer Hudnut and directed by Greg Yaitanes. Hudnut also serves as executive producer and showrunner. “Yellowstone” mastermind Taylor Sheridan executive produces along with David C. Glasser for 101 Studios as well as John Linson, Art Linson, Grimes, Ron Burkle, David Hutkin, Bob Yari, Greg Yaitanes, Michael Friedman, and Keith Cox. Paramount Television Studios will produce. The series will be distributed by Paramount Global Content Distribution.

“Y: Marshals” is not the only “Yellowstone” spinoff in the works. There is also a new series centered on Beth and Rip, which recently added Annette Bening to its cast. Sheridan is also prepping the latest prequel series, “1944,” for Paramount+.

(Pictured, left to right: Arielle Kebbel, Ash Santos, Tatanka Means, Brett Cullen, Gil Birmingham, Mo Brings Plenty, Brecken Merrill)