Partner from 1993 to 2024 is Ben Daniels. They met during a London stage production of Joe Orton's "Entertaining Mr. Sloane".
From May to July 2014 he performed as Marcus Andronicus, brother of Titus, in Lucy Bailey's revival of her original 2006 production of Titus Andronicus at Shakespeare's Globe Theatre.
Gelder's husband Ben Daniels stopped working to take care of him, and remarked that he dealt with his "dreadful illness with such bravery".
He was known for his numerous stage and screen roles, including Mr. Dekker in Torchwood: Children of Earth and Kevan Lannister in Game of Thrones.
He used his mother's maiden name as his stage surname,.
Passed away from bile duct cancer on May 6th, 2024 at the age of 74 years old.