He is known for his roles as Qyburn in the HBO series Game of Thrones, Harold Macmillan in The Crown, Clement Attlee in A United Kingdom, Chief Superintendent Bright in Endeavour,[2] and Major Partagaz in Star Wars: Andor.

[7] Lesser went to the Royal Academy of Dramatic Art from 1974 until 1976,[3] and on graduation in 1977[8] was awarded the Bancroft Gold Medal as the most promising actor of his year.

However he continued to win roles on stage, including as Stanley in Harold Pinter’s The Birthday Party, Petruchio in The Taming of the Shrew, Rover in Wild Oats and Brutus in Deborah Warner's Julius Caesar in 2005.

Other books range from John Milton's Paradise Lost, Homer and Rumi[10] to contemporary novels by Robert Harris (Fatherland) and Philip Pullman.

[11] In 2013, during the third season of the HBO Max series Game of Thrones, Lesser began playing the recurring role of Qyburn, an enigmatic mad scientist who served as part of the retinue of Cersei Lannister (Lena Headey).

[16] Lesser portrayed Thomas More in the BBC mini-series Wolf Hall, and received a nomination for the British Academy Television Award for Best Supporting Actor for his performance.