Spitter is a green, bulbous alien. He resembles a puffer fish. He has 3 spikes sticking out the top and bottom of his head. His mouth covers mostly the upper front of him, which is filled with dull colored, pointed teeth. His eyes are connected to the corners of his lips.
In Ultimate Alien, Spitter looks exactly the same except he now has green eyes and white teeth. He wears the Ultimatrix symbol on his stomach.
Spitter is the second alien in Ben 10: Ultimate Alien not to have the Ultimatrix symbol on his chest, having it above his waist instead. The first is Murk Upchuck.
Spitter's slime can conduct electricity.
Spitter came to be from re-purposing one of Perk Upchuck's prototypes, similarly to Articguana (albeit, his coloring was changed during re-purposing).