Although there is a lot known about Rome's insane third Emperor Caligula (12 41 AD), there's not a lot known about the horse he wanted to make a full-fledged legal politician, Incitatus. In the popular mini-series "I, Claudius", Incitatus was a grey colt who was promoted to Senator, but it's thought Inciatus did not get that far in his political career. But it is not known how much about Incitatus and Caligula is truth and which was legend.
It is known that Incitatus was a racehorse and not a warhorse such as Alexander The Great's beloved Bucephalus. On the day before the race, Roman soldiers would clear the area around Incitatus' home in order that loud sounds wouldn't disturb his rest. Caligula's treating the horse like a person was one of the gentler manifest stations of his mental instability. It's also been written that Caligula and Incitatus were lovers, which would certainly be cruel to the horse if the allegation ever turns out to be true.
Where Incitatus Lived
The most details that have passed down through history about Incitatus was about the lavish stable where he lived during the time of Caligula's brief reign. According to the historian Seutonius, Incitatus lived in a stable made of marble, had a stall made of ivory, a collar with jewels and wore royal purple (which only the emperor's family was allowed to wear). Incitatus also had a house, furniture for his guests and slaves.
According to Cassius Dio's writings, Incitatus ate barley mixed with fold flakes and any titbit Caligula gave him from the lavish dinner parties held in the palace or Incitatus' house. It's also said that Incitatus drank his water and wine from a golden goblet. Caligula would use similar golden goblets to toast his racehorse's health. Caligua was said to have urged everyone around to worship Incitatus as a god.
Legend has it that Incitatus was "married" to a mare named Penelope, who was most likely a racehorse, too.
What Did He Look Like?
We have no idea what Incitatus looked like, as no artistic representations of him exist nor did Seutonius or Cassius Dio describe him in any way. These two historians never say Incitatus because they lived centuries after Caligula's death. Based on the fact that he was a racehorse and Rome did rule Greece and the Middle East (the best sources for horses in those days), Incitatus most likely was about fourteen hands high, slim of build, thin of mane and tail and possibly had a straight or dished profile.
Sadly, due to Caligula's unpopularity, Incitatus was most likely executed after the emperor's overthrow. Considering that horses were not made to eat gold flakes, drink wine or live in a house with furniture, death was probably a relief.