He's a plastic Games Workshop Nurgle Champion and seems to be hugely popular as a blank canvas for all sorts of conversion work. I've seen him turned into a space marine, a thug, a pirate, a demon and even a crazy hovering Baron Harkonnen type by Jacob Rune Nielsen here:
I decided to have a go myself. He reminded my of another chunky 40k model, the old Genestealer Patriarch. Back in the day, the Patriarch was a massive fat purple genestealer, like a cross between H.R. Giger's Alien, Don Corleone and Barney the Dinosaur. The thuggish, bulky Nurgle champion seemed like a good starting place to make my own patriarch.
I made him a new stomach and head out of green stuff, ridged like a tubby version of a purestrain genestealer's underside. I tried to make him look sluggish and menacing:
I think he looks quite threatening in this photo. I'm not sure why he only wears metal boots, a shoulder pad and a loincloth, but that sort of outfit is hardly unusual in the 40k world. I often wonder how 40k characters sit down, or go to sleep. Anyhow, I gave him a (for me) detailed scenic base and got on with the painting.
And here he is, in all his seedy, dribbly glory. The thing dangling between his legs is a tail taken from a plastic skaven.
I showed this model to a friend of mine, who said "He looks like Mr Bump from the Mr Men". Since then, I've never been able to get the connection out of my mind. Thanks, mate!