Graser10 found three skeleton horses on Jardoon's island in the vanilla survival Minecraft series called The Deep End. Graser originally gave one to StaceyPlays. It is assumed that he kept the other two. Stacey, not wanting to face legal charges, gave her horse to Sparklez. It went unnamed for the rest of the episode.
The following episode, Logdotzip pulled a prank as revenge for Jardoon writing coordinates into the chat to keep track of his spawn point in the Nether. Logdotzip mistakingly thought that he was supposed to go to the coordinates. He went to those coordinates in the overworld and got mad when he found nothing there. He stole Jardoon's skeleton horse and presented three riddles to find the three coordinate positions where Jardoon could find the horse. Logdotzip also referred to the horse as "Ugly", and Jardoon decided to keep with that name. Over on Logdotzip's channel, he explains that he was not calling the horse Ugly. Rather, he was insulting Jardoon. As of now, no one has informed Jardoon of his misconception.
Ugly dies before episode 14 in the house remodelling prank. He is replaced with another skeleton horse nametagged 'Ugly Too' (not to be confused with Ugly 2.0)