Roger William Allam (born 26 October 1953) is a British actor who has performed on stage, in film, on television and radio.

He is also known for his roles as Illyrio Mopatis in the HBO series Game of Thrones, Royalton in Speed Racer, Lewis Prothero in the 2005 adaptation of V for Vendetta and as Peter Mannion MP in The Thick Of It.

He won an Olivier Award as Best Actor 2001, for his role as Captain Terri Denis in a revival of Privates on Parade, opening in December 2001 at the Donmar Warehouse, Covent Garden.

In December 2004 and January 2005, Allam appeared as the villainous Abanazar in a pantomime of Aladdin at the Old Vic theatre, co-starring Ian McKellen, Maureen Lipman and Sam Kelly.

In August 2005, Allam appeared in Blackbird by David Harrower alongside Jodhi May at the Edinburgh Festival in a production by German star director Peter Stein.

In February 2007, he performed in the 1960s farce Boeing-Boeing at the Comedy Theatre in the West End, co-starring Mark Rylance, Frances de la Tour and Tamzin Outhwaite.

By 2018 Allam had portrayed his central character in five additional well-received series, which are also aired in America as part of the PBS Masterpiece Mystery!

Allam has also reteamed with Stephen Frears in Tamara Drewe, the film version of Posy Simmond's popular comic strip.

In the closing chapter of his Timebends autobiography (1987) Arthur Miller writes of Allam: "To play Adrian....in the 1986 Royal Shakespeare Company production of The Archbishop's Ceiling, Roger Allam gave up the leading role as Javert in the monster hit Les Misérables because he had done it over sixty times and thought my play more challenging for him at that moment of his career.

[12] Since January 2020, Allam has co-starred with Joanna Lumley in the BBC Radio 4 comedy drama series Conversations from a Long Marriage.