Geldoff is a Latverian orphan who was experimented on in the womb, gaining the ability to generate explosive orbs of energy. He battles Spider-Man, who attempts to persuade him into becoming a hero, before being sedated by the X-Men. After learning of Geldoff's origins, Professor Xavier plans to present him to scientific organizations and the United Nations as proof of illegal genetic research.1
Geldoff can generate and discharge explosive energy balls, and appears to be resistant to his own powers.2
Geldoff's Earth-616 counterpart first appeared in Avengers: The Initiative #8 (February 2008), and was created by Dan Slott and Christos Gage and artist Stefano Caselli. This version is a member of the Fifty State Initiative before being killed by a Super-Skrull during Secret Invasion.34
A separate character based on Geldoff named Geldhoff appears in Inhumanity. This version is an Inhuman whose powers are activated after Attilan is destroyed, releasing the mutagenic Terrigen Mist into Earth's atmosphere.5
Ultimate Spider-Man #40-44 (July - October 2003) ↩
The Official Handbook of the Ultimate Marvel Universe 2005: The Fantastic Four & Spider-Man ↩
Avengers: The Initiative #12 (June 2008) ↩
Richards, Dave (September 17, 2008). "SPOILERS OF WAR: Secret Invasion #3". Comic Book Resources. Archived from the original on September 17, 2008. https://web.archive.org/web/20080917042050/http://www.comicbookresources.com/?page=article&id=16695 ↩
Uncanny X-Men (vol. 3) #15 (February 2014) ↩