Warning: Wikipedia contains spoilers.
In The Animatrix, The Kid is an individual connected to The Matrix who is brought to see the truth by Neo. His circumstance is peculiar in that he had died from a fatal fall prior to being awakened in the real world. His body was somehow able to self-sustain while Neo and the crew raced to locate his person in the real world.
Following the events of The Animatrix, The Kid makes his first live appearance in The Matrix Reloaded. While possessing a minor role at best (with but a few lines of unimportant dialogue, though his handing of the spoon to Neo could signify something greater), his actions in The Matrix Revolutions were integral to the salvation of Zion. During the Final Battle for Zion, The Kid piloted the deceased Mifune's APU and destroyed a chain which held the gate closed such that the Hammer could enter the dock and set off its EMP.
Prior to The Matrix Revolutions, some had speculated as to whether or not The Kid was Neo's successor as "The One", however, there is at this point no conclusive evidence to support this theory.
The Kid (1921) is a Charlie Chaplin movie.