“That big bloke from Slytherin who looks like a sloth….” (GF16).
While a member of the Inquisitorial Squad (and coincidentally just before a big match with Gryffindor), Warrington suffered an attack that left him with a horrible skin ailment which made him look as though he had been coated in cornflakes (OP30).
Other canon notes and references
He must have been at least seventeen on October 30 1994, to have put his name in the Goblet of Fire. Given that he was still at school the next year, he presumably started at Hogwarts in 1989 (unless he had to retake a year).
Warrington is a surname of Anglo-Saxon origin, coming from either the town of Warrington in Buckinghamshire or the one in Lancashire. It derives from Olde English waer "pledge", heard "hardy, brave, strong" and tun "homestead, settlement" (Internet Surname Database).
He is probably the same as the C. Warrington who checked Quidditch Through the Ages out of the Hogwarts school library (13 November) (QA).
There could be a link between Warrington's cornflake-like skin complaint and the snuffbox of Wartcap powder from No. 12 Grimmauld Place, that gave Sirius's hand an 'unpleasant crusty covering' and that George Weasley subsequently pocketed (OP6).
According to the Harry Potter Wiki, Warrington's first name is Cassius. This detail was on a film prop in Harry Potter Wizard's Collection. While this does match the first initial seen in Quidditch Through the Ages, it cannot be considered canon.
Lexicon list of Chasers
From the Web
Harry Potter Wiki: Cassius Warrington