The actor, who had a brain tumor, died at home.
Paul Ritter has died at age 54. The actor died the night of Monday, April 5, of a brain tumor, his rep tells ET. Ritter's wife, Polly, and sons, Frank and Noah, were with him at home at the time of his death, his rep adds.
In a statement to Variety, Ritter's agent expressed "great sadness" over his death, adding that the actor "died peacefully at home."
"Paul was an exceptionally talented actor playing an enormous variety of roles on stage and screen with extraordinary skill," Ritter's agent said in part. "He was fiercely intelligent, kind and very funny. We will miss him greatly."
Actress Helen Mirren, who starred opposite Ritter in the stage production of The Audience in 2013, shared a statement to ET honoring the actor's memory.
"Paul was a deep and thoughtful actor who was truly wonderful to work with," Mirren reflected. "Sensitive, intelligent and generous, he will be terribly missed by all the fraternity who make drama."
The Tony-nominated, British actor had memorable roles both onstage and onscreen, starring in The Norman Conquests on Broadway and Quantum of Solace and Harry Potter and the Half Blood Prince on the film side.
When it came to TV, Ritter appeared on HBO's Chernobyl, Epix's Belgravia, ITV's Cold Feet, and Channel4's Friday Night Dinner, the latter of which he will be featured in a 10-year retrospective for later this year.
He will also be seen in Operation Mincemeat, Netflix's war drama starring Colin Firth.