Damian was born and raised in England. His parent's are Watcyn and Charlotte Lewis. He has two brothers, named William and Gareth. Also a sister, named Amanda. When Damian was 8 years old, he attended Ashdown House boarding School. That is where he became interested in acting. Before he went to college, he backpacked through Africa. In 1993, he graduated from Guildhall School of Music and Drama. He also attended Eton College. While attending Eton College, Damian played many sports, such as golf, varsity football (soccer), tennis and cricket. At the age of 16, he formed his own theater company and was a stage actor for the Royal Shakespeare Company. In 1998, while riding home on his motorcycle after a stage performance of Much Ado About Nothing, he was nearly killed in an accident. Later on, In February of 2006, he became a trade justice ambassador for one of United Kingdom's oldest charities, Christian Aid. He was voted Britain's 31st Most Sharp Man by the readers of Esquire magazine, in 2002.
Damian married actress Helen McCrory, on July 4, 2007. They have a daughter, named Manon. She was born on September 8, 2006. On November 2, 2007, they welcomed their second child, a baby boy named Gulliver.