Williams grew up in Central London in a working-class family. He served in the Royal Engineers during World War II, where he first became interested in becoming an entertainer. After a short spell in repertory theatre as a serious actor, he turned to comedy and achieved national fame in "Hancock's Half Hour". He sustained continued success throughout the 1960s and 1970s with his regular appearances in "Carry On" films, and subsequently kept himself in the public eye with chat shows and other television work.