|This article is about Carl Greer. For his daughter, see Doc II. For a list of other meanings, see Doc (disambiguation).|
Carl Greer, known to his friends and allies as Doc, is perhaps the ideal medic. Compassionate, warm and empathetic, Doc knows that understanding and kindness can be just as important as a skilled hand or the right medicine. He's a good friend to his comrades-in-arms, and a good father to his daughter Carla; through a life of practicing medicine, he has learned the value of humility and care. But beneath it all, he holds a dark secret, one that could ruin everything if it were to get out...
Prior to becoming one of the G.I. Joe team's medics, Doc worked across the globe as an aid worker, including as part of the UN's tsunami aid response; as part of this job, he used his fluency in Swahili, Turkish and Spanish. During this time he learnt the importance of humility when a woman, whose family he had promised that she would survive, died after unforeseen complications during surgery.
When Alpine had to have his legs amputated after contracting gangrene during a mountain mission, Doc oversaw his hospital stay, and was responsible for getting him his new prosthetic legs. Doc was also responsible, along with Lifeline, for overseeing Duke after he contracted the Orphiophagus retrovirus, and reluctantly treated him to allow him to go after Rodrigo Vargas, the man responsible for infecting him. When Doc realised that the virus cased violent dementia in its later stages, he tried to stop Duke and Snake Eyes from leaving, but by the time he could they had already left under radio silence.
When Snake Eyes returned to the Joes after his apparent defection to the Arashikage, Doc was responsible for his medical treatment, and made a wry remark about how none of his many, many injuries were unusual for the ninja.
At some point, Doc's daughter Carla followed him into G.I. Joe as a medic, taking on his codename. When Doc Junior was made a part of Duke's public unit of "celebrity soldiers", Doc Senior tried to give her some fatherly advice before she deployed, but mostly managed to come across as a fussing nuisance.
After G.I. Joe broke ties with the United States government, Doc Senior became the chief medic on the Lemuria, G.I. Joe's home base. He and Grand Slam worked on a method of detecting Dire Wraiths, but couldn't successfully develop one, with their scanner recognising both of the Docs as being Wraiths. After Skywarp insisted that the Joes fix his inactive teleportation systems, Doc and Grand Slam agreed to help; however, when Skywarp attempted to test his teleportation systems, it malfunctioned and caused the machines he was attached to to explode. Doc threw his body in front of Grand Slam to protect him from the shrapnel, but in the process, he was revealed to really be a Wraith. As Doc fell unconscious, wounded from the shrapnel, he asked Grand Slam to tell his daughter that she could "be whatever she wanted". Lifeline and Grand Slam managed to stabilise Doc, over Skywarp's objections; though the ex-Decepticon insisted that as a Dire Wraith the medic couldn't be trusted and should be killed, Scarlett and Grand Slam refused, pointing out that he had only revealed himself to save Grand Slam's life.
- Doc's first name has never been given in IDW continuity, but given the shared surname, it's probably safe to assume that he has the same full name as his classic counterpart.