Sal is the overgrown cockroach that worked as a chef for Girl Stinky and as a security guard to Paiperwaite's Museum of Mostly Natural History. He is one of major characters in the last three episodes of Sam & Max Season Three.
Sal is first mentioned in Season Two, when he's said to be Stinky's cook. However, he was never seen in person, so even his existence was doubted. Third episode of The Devil's Playhouse reveals that he's, in fact, a man-sized cockroach wearing a security uniform.
Sal first visually appears in They Stole Max's Brain! in which he is Anton Papierwaite's employee as well as the "Museum of Mostly Natural History" guard. Sal seems quite relaxed and normal, though he believes his boss is a loser. He threatens to throw Max out, before Sam places Sammun-Mak's brain in his brainless body. Sal is quite loyal to his boss; he is so loyal that when Sam replaced his headset with the tour guide headset (voiced by Papierwaite) and Sam makes the headset tell him to poke the eyes of one of General Skun-ka'pe's minions; Sal follows, and is attacked by the minion (breaching Skun-ka'pe and his boss's relation). He is hospitalized, though in Sammun-Mak's alternate reality he works as the boss of the gift vault.
In Beyond the Alley of the Dolls, he resigns from his job at the museum, because of being beat up by General Skun-ka'pe's army so he could take a job stacking crates, while surrounded by Samulacra. He draws a picture of Grandpa Stinky's favorite cake under Sam & Max's request, which Max can use the rhinoplasty toy with to transform to. It is later revealed that he and Girl Stinky are having a relationship, and are plotting to knock out Grandpa Stinky. Before they can say anything else, they are taken under Charlie Ho-Tep's control. While being controlled, Sal topples from the center into the bottomless abyss yet as shown later, he survives. An extra scene after the credits shows Girl Stinky crying out for Sal.
Sal is revealed to be alive and well in The City That Dares Not Sleep where he runs from Sam at the beginning of the episode. Later, he meets with Stinky on the roof of Boscotech Labs and it is revealed that the two have been scheming together for 'decades'. However, he is suddenly abducted by giant Max when Sam makes him hungry for cockroaches. Sal agrees to help Sam take control of the arms by taking advantage of his guilty conscience. At last, Sal suffers from radiation poisoning and lays down on the couch in Max's brain where he dies... However, a figure of a giant cockroach appears in the "crimefighting" ending of episode 5. It's unclear whether it's Sal or another one of his kind. Sam, when he clicks on the deceased Sal, decides to make sure his sacrifice is heard.