Neutron
Neutron, an alien member of the Shi'ar Empire's Imperial Guard briefly used the name Quasar. He fought Quasar in Quasar vol. 1 #33 (1992) and again in #45 alongside Sergei Krylov. Both Krylov and Neutron had been trapped by Quasar in a realm of potential energy called the Quantum Zone, and both were seeking revenge. Quasar eventually tricked Sergi into abandoning the fight and Neutron was picked up by his team, the Imperial Guard, abandoning Quasar.
Read more about this topic: Quasar (comics)