He is one of the UK's most recognizable voiceover artists due to his heavy North-East England accent (which he often exaggerates for effect).
He has been a continuity announcer at Channel 4 since the late 90s.
As well as Big Brother (UK), Marcus has narrated spin-off shows Celebrity Big Brother and Teen Big Brother: The Experiment.
Marcus has featured in more episodes of Big Brother (UK) than anyone else. Davina McCall, the series' main presenter only appears on Fridays while contestants only appear for one series at a time.
Has had TV bit parts in shows such as The Bill and London's Burning.
Bentley was the unseen host on a Sky One quiz show, Dirty Money.
Marcus rarely makes appearances on camera.
During the 2006 series' of Big Brother (UK), Marcus worked 7 days a week for the length of the show's run which is over 10 weeks.