Rhomann Dey is a Corpsman in the Nova Corps, the planet Xandar’s military force. Dey is a loyal and trusted officer but his by-the-book attitude takes a detour when he develops an unlikely rapport with Star-Lord.
While Gamora, Rocket, and Groot were fighting against Star-Lord, the Nova Corps arrested the trio, on that Rhomann Dey recognizes Peter as Star-Prince, Peter responds that Star-Lord but Rhomann Dey tells him to calm down because it is not a good nickname. Dey along Saal presented in Kyln the future Guardians of the Galaxy.
After Yondu and Star-Lord stamped a deal, Star-Lord communicates with Dey to report that the Guardians help to stop the great accuser kree, Ronan. Dey reported this to the Nova Prime, Irani Rael.
After the battle, Dey is promoted and presented the Guardians his rebuilt ship. Later, Dey returns to his home and is reunited with his family.
Rhomann Dey appears in the Guardians of the Galaxy episode "Origins," voiced by Jeff Bennett. He was present with Titus on Xandar when Drax the Destroyer turned himself over to the Nova Corps in exchange that the aliens that were taken prisoner by Ronan the Accuser were returned to their own planets. In the episode "Space Cowboys," Rhomann Dey and the Nova Corps members confronted the Guardians of the Galaxy when they were tipped off that they were taking the Moombas to the Grandmaster on Conjunction. He then witnessed as the Moombas opened a portal that dragged the Moombas and the Milano to an area close to Conjunction. When Yondu's Ravagers bring the explosive Moombas close to Knowhere on Grandmaster's behalf, Rhomann and the rest of the Nova Corps was contacted by Cosmo the Spacedog to help the Guardians of the Galaxy. Cosmo told Rhomann about Collector being behind the Moomba trafficking causing Rhomann to contact Collector about it. Collector disavowed any knowledge of that and got away. While making sure that the Guardians of the Galaxy transported the Moombas to a safe location, Rhomann and the Nova Corps then pursued the fleeing Ravagers. In the episode "Right Place, Wrong Time," Rhomann Dey was at a Nova Corps outpost when the Guardians of the Galaxy give him a sarcophagus that was previously in the possession of Thanos. In the episode "Nova Me, Nova You," Rhomann Dey and the Nova Corps officers with him confront the Guardians of the Galaxy when the detected the Nova Centurian Helmet that Sam Alexander is wearing being on the Milano. After briefly being entangled by the tractor beams of the Nova Corps ships, Sam escapes with the help of the Guardians of the Galaxy. When Sam and the Guardians of the Galaxy are fighting J'son on Earth, Dey shows up with the Nova Corps where they join the fight. Following Sam flying J'son up into the atmosphere where he goes supernova a second time, the Guardians of the Galaxy confront Dey about not mentioning about Jesse Alexander being a Nova Centurian. After mentioning that they had to train him upon being unable to get the helmet off him, Dey agrees to let Sam be trained on Earth.