Captain Sweatpants. He usually appears in the background and at geek related events. He is tall, thin, has brown hair and wears a beige sport coat that is too small for him. He is portrayed by Owen Thayer.
In "The Creepy Candy Coating Corollary" (S03E05), Lonely Larry first appears where he and Captain Sweatpants were partners playing "Mystic Warlords of Ka'a" and are beaten by Sheldon and Raj in the comic book shop tournament.
In "The Justice League Recombination" (S04E11), Larry is seen in the Comic Book Store.
In "The Russian Rocket Reaction" (S05E05), Larry is a guest at Wil Wheaton's house party.
In "The Tangible Affection Proof" (S06E16), Larry is in the Comic Book Store. This was his last appearance in the series.