Jack Flint is a character appearing in the latter part of The Invisibles
by Grant Morrison
, published by DC Comics
Flint, along with his colleague George Harper is a member of Scotland Yard's Psychic Investigation Squad, Division X newly reformed and proudly "taking the PIS into the new millennium".
Flint is a cover personality based on Jack Regan of the Sweeney, a 1970s British TV show, and the first of its kind to be truly representative of real, occassionally brutal, police and criminal methodology and behaviour. He even looks a lot like John Thaw, who played Regan in the television series.
He reports to Paddy Crowley "to rhyme with foully, not like dear old Aleister, who was holy".