An Alley Cat race is an informal bicycle race. Alley Cats almost always take place in cities, and are often organized by bicycle messengers. The informality of the organization is matched by the emphasis on taking part, rather than simple competition. Many Alleycats present prizes for the last competitor to finish (sometimes known as Dead Friggin' Last or DFL). The first race to be called "Alley Cat" was held in Toronto on October 30, 1989 and continued, in its original form, around Halloween and Valentine's Day for the following five years. In 1993, when Toronto messengers shared Alleycat stories at the first international messenger race (C.M.W.C Berlin), the name and the concept spread far and wide. Regularly organized Alleycats can be found in cities across North America, Europe and Asia. Many smaller cities with no cycle messenger population are also home to alleycats run by the burgeoning urban cyclist subculture.

Alley Cats reflect the personality, contemporary environment and level of competition based on the organizer(s). Races may be less competitive and designed to be enjoyed by the local messenger community around set holidays, such as NYC's July 4 Alleycat, or they may be extremely grueling and designed to eliminate all but the fastest and best overall messenger.