Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Equus (comics) Equus (comics) Equus is a fictional comic book supervillain, a cyborg mercenary in the DC Comics universe who serves as an opponent of Superman. Created by writer Brian Azzarello and artist Jim Lee, he first appeared in "Superman" #206 (August 2004), which was published in June 2004 as part of the "" storyline. Equus first appears in the third issue of the year-long "" storyline that ran in "Superman" in 2004 and early 2005. A prototype for the OMAC Project, he comes into conflict with Superman when the superhero discovers that "The Vanishing", an event in which one million people