Instagram/Steven Yeun & Lewis Pullm Celebrity Discover the MCU's new Sentry: his villainous turn, Lewis Pullman's casting, and why Steven Yeun originally had the role. April 1, 2026 AceShowbiz - One of the new characters introduced in the Marvel Cinematic Universe in 2025 was Thunderbolts' Sentry, portrayed by Lewis Pullman. The MCU version of Sentry notably diverged from his traditional comic book origins.