Pratchett seems to have derived the name from "Churm Rincewind", a fictitious person referred to in early Beachcomber columns in the Daily Express.
Pratchett's Rincewind is a failed student at the Unseen University in Ankh-Morpork, and spends just about all of his time running away from various bands of people who want to kill him for various reasons.
He started out, in the first book, The Colour of Magic, as a guide for the tourist Twoflower, who hailed from the Counterweight Continent; a continent across the disc from the 'hub' continent where Ankh-Morpork is situated. He and Twoflower wander around for quite a while, and get chased by everything from the personification of Death to a necronomicon-esque creature named Bel-Shamharoth.
The first book ends with a literatal cliff-hanger when he and Twoflower are thrown off the edge of the Disc by astronomers who want to know the gender of the turtle A'tuin upon which the disc rides, and have designed a space-ship to do so.
They both survived, for rather complicated reasons involving the structure of the universe, and Rincewind became a recurring character in the series.
Rincewind is most frequently seen with his hat with the word WIZZARD emblazed across it in sequins (this may be a reference to Roy Wood's rock band Wizzard) and his Luggage, which has hundreds of little legs and follows him everywhere. He widely believed to be an elderly man, but the first two books describe him as being young- although he must have aged some along the series.
Rincewind appears in: