R.I.P. Chernobyl and Friday Night Dinner actor Paul Ritter

As reported by the Associated Press, actor Paul Ritter—best known to American audiences for playing haggard and impatient nuclear engineer Anatoly Dyatlov on HBO’s Chernobyl and the wizard Eldred Worple in Harry Potter And The Half-Blood Prince—has died from a brain tumor. He was 54.

In England, Ritter was possibly better recognized from his work on the comedy series Friday Night Dinner, on which he played Martin Goodman, the patriarch of a Jewish family living in North London that would have their weekly Friday dinner derailed by wacky hijinks. In a statement, Friday Night Dinner creator Robert Popper referred to Ritter as a “lovely, wonderful human being,” adding that he was “kind, funny, super caring, and the greatest actor I ever worked with.”

Ritter left an undeniable impression on HBO’s Chernobyl, standing out even among its all-star cast. His character, the thoroughly unlikable Dyatlov, was depicted as the man who was largely responsible for the Chernobyl disaster after he ignored warning signs, and he effectively embodied the limited series’ overarching themes about leadership failures and defending an ideology over defending people. Chernobyl writer Craig Mazin also shared a statement on Ritter, calling him “one of the most gentle, gracious, and brilliant people” he has ever known.

Paul Ritter is survived by his wife and sons.