The son of an insurance broker, London-born Damian Lewis spent a privileged childhood, splitting time between his family home on the famed Abbey Road and at Ashdown House School, a boarding facility in Sussex. He proved a popular student, dividing his energies between sports and appearing in the school's annual Gilbert and Sullivan productions. At Eton, Lewis followed the same pattern; excelling at soccer, cricket and golf while also being actively involved with student drama groups. When it came time for college, he opted to attend the Guildhall School of Music and Drama from which he graduated in 1993.

Just after graduating from drama school, Lewis found a spot with the Birmingham Repertory Company and his professional career was off. Within a year of leaving Guildhall, he had landed his first major TV role, a guest spot as a murder suspect on "Poirot" and got to undertake one of the greatest roles in classical literature, "Hamlet", produced at an open-air theater in Regent's Park. Perhaps ironically, his next major theater role was in another "Hamlet", this time playing Laertes opposite Ralph Fiennes' title character at the Almeida Theatre in 1995. That production proved so popular that it was imported for a limited run on Broadway. allowing Lewis to make his American theatrical debut.

In 1996, Lewis had his first film role, a small supporting part in the Pierce Brosnan vehicle "Robinson Crusoe". For the better part of the next three years, the actor concentrated on stage role, appearing with the Royal Shakespeare Company in "Little Eyolf", "Cymbeline" and "Much Ado About Nothing". While playing Don Juan in the latter, Lewis was involved in a serious motorcycle accident. Fortunately wearing a full-face helmet, he nonetheless was left unconscious for several minutes and suffered a severe concussion. Over the next three months, he underwent enormous mood swings as a result of his injuries, but he had returned to performing only three weeks after the crash.

Having scored good reviews in the dual roles of Cinderella's Prince and the Wolf in the short-lived Donmar production of the Stephen Sondheim-James Lapine musical "Into the Woods" (1998-99), Lewis landed a breakthrough role in the BBC series "Warriors" (1999). Focusing on four British soldiers sent to Bosnia as part of the UN peacekeeping mission, the two-part drama moved Lewis into the spotlight and netted him rave reviews for his role as a soldier who witnesses unspeakable horrors and has trouble returning to "normal" life. (The production aired in the USA on BBC America in 2001 under the title "Peacekeepers",) The actor followed up with a turn as a man whose wife is secretly in love with his brother in the contemporary seven-part drama "Hearts and Bones" (BBC, 2000).

Following his star-making lead in "Band of Brothers", Lewis portrayed Soames in the Granada Television/WGBH remake of the period drama "The Forsyte Saga" (2002). He also landed his first bona fide leading role in the film version of Stephen King's thriller "Dreamcatcher" (lensed 2002). Lewis was cast alongside Timothy Olyphant, Jason Lee and Thomas Jane as Jonesy, one of four boyhood pals who had the gift of telepathy bestowed on them after performing a heroic act.