Ludovic "Ludo" Bagman. Famous Quidditch player, probably slightly younger than Arthur Weasley. Though tall and powerfully built, Ludo even in the 1990s retains the look of an overgrown schoolboy, with round blue eyes, blond hair, and a rosy complexion. As a young man, he was lean and muscular, but after his retirement he put on a lot of weight.
Ludo was a celebrated Beater for the Wimbourne Wasps c.1980. When his Quidditch days were over, he joined the Department of Games and Sports and eventually (c. 1993) became its head. He served in that capacity until his somewhat informal departure from the Ministry in late June 1995 under a cloud of gambling allegations.
At the height of his Quidditch career, Ludo was accused of passing information to Augustus Rookwood, an old friend of Ludo's father, as part of Rookwood's intelligence network. At his trial, Ludo admitted passing the information, but claimed that he didn't realize that Rookwood was actually working for Voldemort. Mad-Eye Moody, for one, had no trouble believing Ludo had been foolish rather than deliberately treacherous, saying he'd always been dim.
Bagman’s downfall came when he gambled heavily on the Quidditch World Cup final of 1994. He attempted to recoup financially by borrowing money from the goblins and placing still more bets. He used leprechaun gold to pay off witches, wizards, and a few goblins to whom he owed money, then spent most of the next year after the World Cup trying to avoid his angry creditors, among them Fred and George Weasley. Ludo's last-ditch effort to recoup was to place a large wager on the underdog in the Triwizard Tournament, Harry Potter, afterward concentrating on unethically using his position as a Triwizard judge to influence the outcome. When the Tournament ended in a draw, Ludo fled rather than face his goblin creditors.
ludo = Latin for "play"
bagman = (Eng. slang) While in the U.S. this carries the sense of "one who collects money, as for racketeers", in the U.K. it carries the meaning "traveling salesman."