|Appearance:||Brown hair. red shirt, tan pants, backpack|
Bloo (best friend and creator)
Mac is the creator of Blooregard Q. Kazoo and younger brother of Terrence. Like both of them he debuted in the movie Foster's Home for Imaginary Friends House: of Bloo's. Mac created Bloo when he was 3, so Bloo is 5-years-old. Unlike Bloo, Mac is good at paddle ball and obeys what rules are given to him. Even Mac has his flaws, and a major one is when he eats anything with a little sugar in it. Mac begins acting crazy and goofy after he eats the sugar, hungry for more.
He almost always seems to know what to do if there is a problem. Mac is generally good-hearted, intelligent and well-meaning and is often the voice of reason among his friends (especially Bloo) when they are about to make a decision. However, his good nature tends to make him somewhat naive. He is very attached to his imaginary friend Bloo and it is shown in episodes such as "House of Bloos" and "Duchess of Wails" that his biggest fear is never seeing him again because Bloo is what keeps him happy and cheerful and vice versa. Mac's greatest vice is sugar as he becomes extremely hyperactive to the point of a rabid mania if he eats any; once in this state, he will often become obsessed with seeking any other source (and will also sometimes run around naked or in his underwear). He and Bloo are great friends. Mac also has a Rivaly with Frankie.
Mac has light skin and brown hair, he wears a a dark crimson T shirt, tan pants, dark green backpack, black sneakers with white markings and a white sweater underneath his shirt.