There is a large portion of the gaming community that takes advantage of in-game horse-naming functions - featured in The Legend of Zelda: Breath of the Wild and Red Dead Redemption 2, to name a few. You can’t, however, name your horse in The Witcher series, because Geralt’s steed is the horse with a name.
Aside from the well-known collection of glitch memes attached to the Witcher’s mount, Roach has been Geralt of Rivia’s name for all his steeds. His horse barely appears during CD Projekt Red’s first two games of the series, but The Witcher 3: Wild Hunt showcases her more prominently. Between her bay hair and brown eyes, Roach belongs in the hall of horses in video games, alongside Epona and Agro. Her name sounds a little rough around the edges, but Geralt’s reasoning is just.
In Polish author Andrzej Sapkowski's third book - Baptism of Fire - from The Witcher novel series, Geralt confirms that he names all of his horses Roach, implying that there has been many throughout his extended lifetime. "Płotka" is the Polish term for a female horse, and it’s also an informal version of the word "płoć," which literally translates to “roach” or “roachy.” Geralt is known for favoring mares over stallions, therefore, the monster hunter’s preference ties his steed’s name to Polish terminology. The ancient vampire Regis points out Geralt’s affection towards his horse in Baptism of Fire also, saying "You are not even able to get rid of this vicious mare to get another horse…You do not leave anyone behind."
The Witcher’s bond with Roach is so touching that the Netflix series showrunner Lauren Schmidt Hissrich wanted to emphasis their relationship in the show. Geralt’s live-action counterpart Henry Cavill was even allowed to pick his own horse to sustain the show with. Hissrich wanted the audience to be able to tap into that unspoken bond between the pair, without overselling it through dialogue. She wanted there to be an off-screen connection that would flourish when the cameras began rolling.
Roach’s in-game legend precedes her, however, as another horse from The Elder Scrolls V: Skyrim is trotting in her footsteps. A redditor documented an in-game glitch showing a horse falling randomly from the sky, which is a little bit of a level up from Roach’s roof-hopping.
Source: Looper