Kai Alexander

Kai Alexander (born 7 June 1997) is an English actor. He gained recognition for his standout performances portraying Lyle Jennings in Dept. Q and World War II veteran Sgt. William Quinn in the Steven Spielberg and Tom Hanks war drama, Masters of the Air. He began his career in the Channel 4 comedy series Catastrophe and is set to appear in the feature film Anxious People.

Early life and education Alexander was born and raised in the Midlands. A musician from a young age, he learned piano as a child and later played drums in youth jazz orchestras. As a child Kai appeared in a Honey Monster TV commercial directed by Garth Jennings. At 16, he relocated to London after earning a place at the Arts Educational Schools (ArtsEd) to train in acting.

Career After leaving drama school, Alexander landed his first lead screen role as William in the BBC Three drama short Oakwood. In 2017, he joined the cast of the award winning Channel 4 comedy Catastrophe in the recurring role of Jeffrey, the on-screen child of characters played by Ashley Jensen and Mark Bonnar. In 2019, he reprised his role in the fourth and final season of Catastrophe and later appeared in Netflix's The Stranger, an adaptation of the novel by Harlan Coben.

In 2022, he portrayed Richard Branson in the Hulu and Disney+ miniseries Pistol, directed by Danny Boyle and created by Craig Pearce. Alongside Karen Gillan, he was cast to voice a lead role in the unreleased animated series Rhona Who Lives by the River also for Disney alongside 20th Television Animation.

Alexander played Sgt. William Quinn in the 2024 Apple TV WWII miniseries, Masters of the Air, produced by Steven Spielberg, Tom Hanks and Gary Goetzman. Esquire described Alexander's performance as his "big break". The role required extensive physical training, with Alexander performing all of his own stunts, including a parachute sequence.

In 2025, he played Lyle Jennings in Scott Frank's adaptation of Jussi Adler-Olsen's Dept. Q for Netflix, receiving critical praise for his "spellbinding" portrayal. He subsequently joined the cast of Angels in the Asylum, starring Simon Pegg and Wind of Change, a biopic focusing on the German rock band Scorpions.

In 2026, he was reported to have joined the cast of Sam Mendes's upcoming series of biopic films of The Beatles for Sony Pictures. He will next appear alongside Angelina Jolie and Jason Segel in Anxious People, a feature film adaptation of the 2019 novel by Fredrik Backman, directed by Marc Forster.

Filmography Film Year Title Role Notes TBA Post-production Suspended production Post-production2028 Filming

Television Year Title Role Notes 2017–2019 Catastrophe Jeffrey Beasley 4 episodes 2020 The Stranger Dante Gunnarsson Miniseries 2022 Pistol Richard Branson Miniseries 2024 Masters of the Air Sgt. William Quinn Miniseries 2025 Dept. Q Lyle Jennings Miniseries TBA Knox Animated series

Denotes productions that have not yet been released