Sonic Rebound [Masked Watcher]

Sonic Rebound - Ep 4 [Resilience]: In this adaptation of the the third IDW comic... the story deviates. Sonic and Knuckles defeat Rough and Tumble and all is well. However both are unware of a mysterious watcher viewing the preceedings. For fans of the comic, this figure might look familiar. Especially since they show up much earlier than expected.

Example of:
Early-Bird Cameo