Robert Gwilym was born on 2 December 1956 in Neath, Glamorgan, south Wales, where his family ran a chain of lingerie shops. He is the brother of fellow actor Mike Gwilym, and the two later appeared together on screen in the 1987 drama On the Black Hill, adapted from Bruce Chatwin's novel.
Gwilym built a long career across British television, becoming a familiar face through recurring and guest roles on some of the best-loved series of the 1990s and 2000s. He first appeared in a single episode of the BBC medical drama Casualty in 1990, returning eight years later to take on the regular role of consultant Max Gallagher, which he played from 1998 to 2002. His other television credits include Soldier Soldier, The Bill, Coronation Street, London's Burning, The Professionals and the drama Dancing at Lughnasa.
Alongside his television work, Gwilym has maintained an active stage career, including a 2006 production of Macbeth at the Bristol Old Vic in which he took on co-starring, co-producing and co-directing duties. In 2013 he took on genre film work, playing the lead role of Sergeant Novikov in the found-footage horror feature Frankenstein's Army.
Now based mainly around Bristol, Gwilym continues to work across stage and screen, in a career spanning more than three decades since his earliest television appearances.