John Gibb Marshall (11 January 1953 – 2 November 2020), better known by the stage name John Sessions, was a British actor and comedian. He was known for comedy improvisation in television shows such as Whose Line Is It Anyway?, as a panellist on QI, and as a character actor in numerous films, both in the UK and Hollywood.
Sessions died of a heart attack at his South London home on 2 November 2020, aged 67. The day after he died, Danny Baker described him as "terrific company and always a true talent". The team behind the BBC television programme QI praised his "incredible wit and encyclopedic knowledge played a huge part in the show's history."