Films:
* The Scarlet Pimpernel (1934): Played Chauvelin, the antagonist.
* The Mystery of Edwin Drood (1935): Played Neville Landless.
* The Prisoner of Zenda (1937): Played Fritz von Tarlenheim.
* The Adventures of Robin Hood (1938): Played Will Scarlet.
* The Phantom Creeps (1939): Played The Phantom.
* The Adventures of Sherlock Holmes (1939): Played Inspector Lestrade.
* The Private Lives of Elizabeth and Essex (1939): Played Sir Walter Raleigh.
* The Invisible Woman (1940): Played Dr. Ted Bruen.
* The Black Cat (1941): Played Dr. Vitus Werdegast.
* The Mad Doctor of Market Street (1942): Played Dr. Frederick Orloff.
* The Mystery of Marie Roget (1942): Played L'Etoile.
* The Strange Case of Doctor RX (1942): Played Dr. Robert Xavier.
* The Spider Woman Strikes Back (1946): Played Dr. Curt Mannering.
* The Brute Man (1953): Played the Brute Man.
Television:
* The Adventures of Robin Hood (1955-1959): Played Prince John (in several episodes).
* The Adventures of Sir Lancelot (1956-1957): Played King Arthur (in several episodes).
* The Adventures of William Tell (1958-1959): Played King Leopold of Austria (in several episodes).
* The Three Musketeers (1959-1960): Played Cardinal Richelieu (in several episodes).
* The Avengers (1961): Played the villain "The Man Who Couldn't Die" in the episode "The Man Who Couldn't Die."
This is not an exhaustive list, but it includes some of his most well-known roles. He also appeared in numerous other films and television shows throughout his career.
He was known for his tall, handsome physique and his ability to portray both villains and heroes. He was a popular leading man in the 1930s and 1940s and continued to work regularly in film and television until his retirement in the 1960s.