Captain John "Ugly John" Black was a side character introduced in the 1968 Richard Hooker novel M*A*S*H. He also appeared in eleven episodes of the CBS-TV series M*A*S*H. The part of Ugly John, who appeared in ten episodes on Season 1, was played by John Orchard, who also appeared later in the series as Muldoon, an Australian Army MP in the Season 8 episode Captains Outrageous.
In the book, Ugly John is actually described as "limpid-eyed, dark-haired, and the handsomest man in the outfit," contrasting his appearance in the show which made his nickname much more literal. He was an anesthesiologist in both versions.