Old Doc Yak was a comic strip by Sidney Smith that centered around a talking goat. The origin of the character was Buck Nix, a goat Smith drew in 1908 for the Chicago Evening Journal. For three years, Nix romanced a she-goat called Nanny. In 1911, when Smith moved to the Chicago Tribune, he introduced a new goat character when Old Doc Yak began as a daily strip on February 5, 1912 with the Sunday page starting a month later on March 10.
Doc Yak was a family man and more mature than Buck Nix. He had a son, Yutch, along with a number of domestic problems. The last Old Doc Yak strip, on February 10, 1917, depicted Yak and his family moving out while wondering who might move into the house next. The last panel showed the empty house. The next day's newspapers, in the space formerly occupied by Old Doc Yak, printed the very first strip of Smith's The Gumps, showing the Gumps moving into the house formerly occupied by the Yak family.
In 1998, Old Doc Yak and Yutch appeared in Valiant Varmints, a one-shot comic book from Shanda Fantasy Arts. A masked figure called Bullethead arranges for the anthropomorphic heroes of the title to be distracted while he goes after a mysterious item; he turns out to be Doc Yak, who just wants his old license plate back (after losing it decades ago to the Gumps).