Not much is described its personality in the game, although it is clear that it obviously does not care about the destruction it causes. When it appears in its full form, its appearance bears a strong resemblance to Chernabog from Fantasia. The Shadow Blot is an enormous, slime-like humanoid comprised of black, blue, and purple shades of ink with glowing green eyes and mouth. Prototypes of the Shadow Blot also included a version called the Storm Blot, intended to be the result of the Shadow Blot and Oswald the Lucky Rabbit fused together.

The character's name was changed when the crew deemed that their revamped Shadow Blot had become very far removed from the original and in keeping with the 'familiar but strange' feeling of the use of some characters. The Shadow Blot was initially a revamped version of the Phantom Blot, but Warren Spector intended on expanding the threat the Shadow Blot posed compared to his camera-stealing motivation in his original appearance.

The Shadow Blot was present in the earliest concepts for Epic Mickey as the force that brought Mickey into Wasteland.