Rob Kirkland is an American actor, filmmaker, and author. He is best known for his recurring work as Sheriff Bill Ramsey on the Kevin Costner lead series "Yellowstone", Cpt. Walter on the Jeremy Renner lead series "Mayor Of Kingstown", and his appearance as Aisha Tyler's (Dr. Tara Lewis) fiancé Doug Fuller in the CBS drama "Criminal Minds". Kirkland has also won writing and producing awards from the New York Ind. Film Fest. for his work on the film F8.