Donnelly Rhodes has died at 80. The Canadian actor passed away from cancer on Monday, CTV News reports.

He is perhaps best known for playing Dr. Cottle on the sci-fi series Battlestar Galactica from 2004 to 2009. Ronald D. Moore, who created the series, took to Twitter to share his condolences.

"Just heard that Donnelly Rhodes, Galactica's own Doc Cottle, has passed away. Very sad," he wrote. "He was a lovely man and I so enjoyed writing for him. Admired his work ever since 'Soap.' He will be missed."

Rhodes starred as Dutch Leitner on ABC's satirical series Soap from 1978 to 1981. Throughout his lengthy career, he appeared in a number of shows including The Golden Girls, Bonanza, Cheers, Taxi, Mission: Impossible (1966), The Young and the Restless, Psych, Smallville and Murder, She Wrote. In recent years, he appeared in Supernatural as Father Simon and in 2016's Arrowverse crossover "Invasion" as Agent Smith. He also appeared in movies like Butch Cassidy and the Sundance Kid and 2010's Ramona and Beezus.

In 2002, he earned the Canadian Cinema & Television's Gemini Award for his work in the Canadian series Da Vinci's Inquest. He received the Gemini Earle Grey Award for Lifetime Achievement in 2006 for his many contributions to the entertainment industry.

Rhodes is survived by his wife, Sarah, and their two children.