Space Phantom

The Space Phantom is a shape-shifting alien foe of the Avengers. He first appeared in Avengers #2 (1963).

Character History
The Space Phantom first traveled to Earth with the intention of having his people invade, though before the invasion could be conducted, he planned to test the might of Earth's greatest defenders first. Taking on the form of the Hulk, the Space Phantom planned to pit the Avengers against one another, destroying them. Eventually outed by Rick Jones, the Avengers fought against the Space Phantom, who took the form of each Avenger at one time or another until he finally attempted to imitate Thor. Unaware that he could not take the form of a god, the Space Phantom inadvertenly banished himself to Limbo instead.

Because of the Space Phantom's meddling, the Hulk was able to see how his teammates so easily turned against him. After hearing the remarks they made and realizing how much they hated him, the Hulk decided to leave the Avengers.

Powers
The Space Phantom has the ability to take the form of any object or person, however while imitating the form of another human being, that being must be banished to Limbo since two identical bodies cannot co-exist. If impersonating a super-powered being, the Space Phantom is capable of accessing the same powers as the being he's impersonating. The Space Phantom can only affect humans, not gods such as Thor.