Swamp Beast is a scientist who transforms into a green monster in Drive-In Me Crazy. He is changed into a real 3D being by Kat's modified lenscap added to the projector.
Lorne is unimpressed but Harley is slimed and finds it convincing. Kat is unable to make it obey and is stepped on.
It is able to uproot a street lamp post (and then throw it 1-handed) then pick up a car with vine tentacles and throw it hard enough to make a hole in a building.
Dennis later calls it "the swamp monster" and then the bog beast when suggesting Coop pit it against the creature from the cosmos.
He throws 2 cars together hard enough that they fragment into pieces and punches the creature hard enough to send it through a wall. He then lifts it and throws it into the top story of a building.
The battle ends when both are eaten by the Glob.