Sheldon

Sheldon is the horseshoe crab behind the counter at Ammo Knights, the weapon shop that has followed the player from Inkopolis Plaza to Inkopolis Square to Splatsville. He is small, bespectacled, and constitutionally incapable of a short answer. Every weapon in the shop comes with a lecture, and every lecture is delivered with the joy of someone who genuinely believes a new Slosher is the most exciting thing that has happened all week.

The Shellendorfs

Sheldon is heir to a weapons dynasty. His grandfather, Ammoses Shellendorf, is credited in-universe with pioneering the ink weapons that made Turf War possible, and the Shellendorf Institute in Inkopolis Square is a museum to the family's work. Sheldon's own contribution is craft: he tunes, tests, and, in the story modes, builds the Hero weapons the agents use.

Supplier to the agents

In Splatoon 2 Sheldon becomes an active part of the New Squidbeak Splatoon, handing Agent 4 a new Hero weapon in each area and fretting about its condition over the radio. In Splatoon 3 he moves to Splatsville, introduces the Sheldon License system that lets players unlock weapons through play, and keeps the agents supplied in Alterna. He treats every prototype like a child sent off to school.

Character

Sheldon is an enthusiast, and the series loves him for it. He is one of the few characters in Inkopolis who thinks about how anything works, and his chatter is the closest the games come to explaining ink physics. He is also earnest to a fault, easily wounded when players skip his explanations, and quietly proud of his family. The joke is that he talks too much. The truth is that he is usually right.