John William Francis Hallam (28 October 1941 – 14 November 2006) was a Northern Irish character actor.
Born in Lisburn, Northern Ireland, Hallam became a familiar face on British television, appearing in many film and television roles including Nicholas and Alexandra (1971), Murphy's War (1971), The Pallisers (1974), Flash Gordon (1980), Dragonslayer (1981), the BBC television adaptations of Prince Caspian and The Voyage of the Dawn Treader (1989) and Robin Hood: Prince of Thieves (1991). He also appears in the director's cut of the 1973 film The Wicker Man as McTaggart.
In 1973 he played the troubled Dr. Peter Conway in the science fiction series Moonbase 3, but his most notable television role was as Thomas Mallen in the drama series The Mallens (1979).
He appeared in the science fiction series Doctor Who as the memorable alien "Light" in the serial Ghost Light (1989). He was also known as Barnsey, the prison cell mate of Den Watts in EastEnders.
On 14 November 2006, Hallam died in Clifton, Oxfordshire, England at the age of 65. He was divorced and had four children.