From Homestar Runner Wiki
n awesome CG dinosaur
The Monster, played by Strong Sad, is a creature (called an octosaurus by Dangeresque), that stalks the Malvies Catacombs. He kidnapped an unnamed woman in a case that drove Dadgeresque mad.
Originally, the Monster was intended to look like a dinosaur with tentacles and laser eyes. However, The Cheat failed to implement the necessary CGI effects, so, much to Strong Bad's disappointment, it simply resembles Strong Sad in a passive optical marker motion capture suit (or, more accurately, painted green with some ping-pong balls attached to him).
Dangeresque killed the Monster by combining his half of the trinket with the other and putting it in a heart-shaped hole in the monster.
 Complete Filmography
Dangeresque 1: Dangeresque, too?, Dangeresque 2: This Time, It's Not Dangeresque 1,
Dangeresque 3: The Criminal Projective (Mini-Site, Dangeresque: THREE in 3D), Dangeresque: Put 'Em on Ice!,
Dangeresque: Puppet Squad (The Curly Fried Caper)
Strong Bad: Dangeresque
Homestar Runner: Dangeresque Too, Uzi Bazooka
Coach Z: Renaldo
Marzipan: Cutesy Buttons, Sultry Buttons
Pom Pom: Professor Experimento
The King of Town: Perducci
Strong Mad (Himself): Killingyouguy
Bubs: Baron Darin Diamonocle
The Poopsmith: Kidnapping Victim
Senor Cardgage: Dadgeresque
Strong Sad (El Dumpo): Hot Tub, The Informant, The Monster, The Stunt Double
The Cheat: Craig, Istanbul, Szechuan Steve
Unknown: The Chief, Kowalski
The theme from DANGERESQUE II: This time, it's not Dangeresque I, Today is Alright 4 2Nite
Nunchuck Gun, Ruby Powered Rocket, Dangeresque Roomisode 1: Behind the Dangerdesque (Walkthrough, Responses)