Gene Belcher is the physician for the Aqua Teens. He bares a strong resemblance to his real-life voice actor Eugene Mirman, and his voice doesn't differ to much from his actual voice.
In "Allen Part One" it is revealed he is also an abortionist. After performing multiple face-abortions on Master Shake's face he steps outside where several anti-abortion protesters are killed by being struck by lightning from Allen, but is quickly killed as well.
In "Lasagna" he informs Carl that every bone in his body has merged into one single "super bone" as a result of drinking a milk shake meant to repair his skeleton after jumping off his roof to get Master Shake's lasagna by Lance's instruction. The doctor first has a condescending view of the shake but later admits it tastes good after taking a sip once Carl jumps several stories to obtain Shake's lasagna.
He returns for his final appearance in "Hospice" to inform Carl that his mother is near death and either requires expensive care or needs to move in with him. His eyes are different in this appearance.
His name has never been mentioned on the show at any point. He went unnamed for several years, however, Dave Willis mentioned his name on Twitter hours before the original airing of "Hospice". His name is a direct reference to the character of the same name from Bob's Burgers, who is also voiced by Eugene Mirman. Mirman's character in Aqua Teen Hunger Force made his debut in November 2006, over four years before his character in Bob's Burgers made his debut in January 2011.