Religion: not determined yet
Name: Greg
Classification:
supporting character
scientist
Publisher(s): 
Pocket Star Books
First Appearance: The Ultimates: Against All Enemies (2007)
Creators: Alex Irvine
Number of Appearances: 1
Occupation: technician
Worked for: Giant-Man
Location: Wilmette, Illinois, USA
Gender: male
Note: assimilated by Chitauri
Greg was an technician who worked for scientist Hank Pym. He was assimilated by a shape-changing alien of the Chitauri race. Greg was working as a technician and assistant for brilliant scientist Hank Pym. Pym was working on developing a way to use ants to detect the Chitauri. It was probably while Greg was already working for Pym that he was killed and replaced by a Chitauri spy.
Of course, Hank Pym did not know that Greg had been replaced by a Chitauri. Presumably the original, real Greg had worked for Hank Pym for some time before being killed, devoured, assimilated and impersonated by a Chitauri spy.
Greg the Chitauri was present when Hank Pym first ran a test of his idea of using ants to detect Chitauri. The ants zeroed in on the Chitauri "Greg," which Hank thought was a mistake - until he realized that "Greg" was actually a Chitauri. Exposed, the Chitauri "Greg" dropped the pretense of pretending to be human and started to transform into his real form. "Greg" battled Hank Pym, but Pym killed him.
The Ultimates: Against All Enemies (2007) (someone disguised or dressed as)