First appearing in The Second Show Ever, he is the "custodian of the cosmos, caretaker of the constellations, sweeper of the corridors of time" destroying "impurities" in the universe. His next target was earth before Sam and Max intercepted. Their use of a "lagomorphic mind-meld" in order to teach Lactose all of humanity's advances and inventions in a short duration, gave him more of a reason to destroy earth since he was disgusted by what he saw.
As he was prepared to destroy earth, Sam and Max resolved to using more convincing methods: a thumb wrestle and then Max ramming head-on into him. He is later seen as a school lunch heater, plotting his revenge.
He returns in The Final Episode as a guard to keep an eye on Sam and Max. He didn't have much to say other than the comical phrase "I see you". after his defeat, at an undertermen time, he found himself on Fang Empire grounds, and then draged down by Krekka and Nedtiki, then Emperor Fang promised great revenge for his services on sam and max.
The school teacher in The Second Show Ever speculated that Lactose may be a middle child.
There are others like him roaming space, but he is unique by having a mustache.
- Sam's Desoto.
- His job as a burger-cook(i dunno... they looked like burgers...)
- Almost everything else.