Prime Video has added three more high-profile actors to the growing cast of its hit series “Fallout,” with Emily Mortimer, Manny Jacinto and Thomasin McKenzie joining the acclaimed video game adaptation for its third season. The trio joins a cast led by Ella Purnell, Aaron Moten and Walton Goggins, while Aaron Paul was previously announced as another major newcomer. Mortimer recently appeared in “Jay Kelly,” Jacinto is known for “The Good Place” and “The Acolyte,” and McKenzie has earned praise for roles in “Jojo Rabbit,” “Last Night in Soho” and “The Power of the Dog.” Based on Bethesda’s popular game franchise, “Fallout” has become one of Prime Video’s biggest successes. Its timeline, which frequently shifts between eras before and after the nuclear devastation, leaves open numerous possibilities for the roles of the latest cast additions.