Nothing is known about, including basic information like his real name. In most of his appearances, he can be seen in the comic book store . Another time he's mentioned is that he attended Stuart Bloom 's art gallery showing (where he disgusted Stuart by touching all the cheese), as well as participating in the Mystic Warlords of Ka'a tournament at the comic book store and going to see the Indiana Jones movie. His nickname, Captain Sweatpants, comes from the fact that he always wears grey sweatpants with a superhero t-shirt (Logo is the "Statesman Star" from the now-defunct "City of Heroes" MMORPG) tucked into it. He is portrayed by Ian Scott Rudolph , who didn't have a credit for any appearance in the role until " The Occupation Recalibration " (S7E13). He appears to be a friend of Wil Wheaton since they went to see the movieand is on Stuart's bowling team.

He was last seen at a high end comic book shop called Capitol Comics Store owned by Jesse (played by Josh Peck), a rival of Stuart's who looks down upon Stuart and his business. Stuart confronts him about not being in his store. Apparently, he only went to Capitol Comics Store for the free popcorn. Also, this episode is the first time in the whole series that Captain Sweatpants ever has a line, "Free popcorn".