Fred Colon is a fictional character in the Discworld novels of Terry Pratchett. He first appears in Guards! Guards!.
Colon is a sergeant in the Ankh-Morpork City Watch, and appears to have been so for a long time. He was a corporal in the Watch at the time Samuel Vimes first joined, and subsequent to this spent some time in the army (the Duke of Quirm's Middleweight Infantry and then the Duke of Eorle's First Heavy Infantry), before returning to the Watch.
He is described on several occasions as "one of nature's sergeants". He is overweight, and prefers to avoid trouble and exertion. He is also rather unimaginative. When not on desk duty (a post he gets more often than other sergeants, due to working out the rota), he generally "guards" bridges or large buildings against theft.
He is currently the head of the Traffic Squad, which also includes his best friend Nobby Nobbs. This role perfectly fits the above described qualities, especially as the Traffic Squad is "self financing" (i.e. they keep the fines).
He is possibly related to Sergeant Dopplepunkt, one half of the town watch in Bad Blintz, Überwald.