Guest-starring Invincible: Comic Book Resources gets to the bottom of the Invincible stand-up that appeared in the season finale of The Shield:

"Kirkman told CBR News that back around the second episode of the season, the production crew for "The Shield" called up the Image Comics offices, located just outside Los Angeles, looking for some super hero stuff to decorate the comic shop with. Image gave them a selection to choose from and Invincible was amongst their choices. The Image folk called Kirkman to get his approval, and being a big The Shield fan himself, he was more than happy to oblige. Kirkman said the image seen in the show is actually a large sized Invincible stand-up, one Kirkman is trying to get his hands on for the upcoming convention season. Kirkman also said somewhere in the store is a poster featuring the comic Capes."