Mac is a bright and somewhat shy 8-year-old boy who visits Foster's. He almost always seems to know what to do when there is a problem. Mac becomes extremely hyperactive to the point of a rabid mania if he eats sugar; once in this state, he will often become obsessed with seeking any other source (and will also sometimes run around naked letting things hang out or in his underwear). Mac also has a crush on Frankie. He is voiced by Sean Marquette.
- Mac will Meet Headdy in Dynamite Headdy's Adventures of Foster's Home for Imaginary Friends. and Dynamite Headdy's Adventures of 101 Dalmatians.