If you're like us, you got and see once you learn that you can mount certain enemies in Horizon Zero Dawn. You may be wondering where you can find these writable enemies, and how many different types there are. If so, you've come to the right place.
Overriding, which is Horizon Zero Dawn's term for mounting, is expanded over time. As you visit various cauldrons, you'll unlock access to a greater breadth of enemies to override.
Although there aren't that many enemies that you can override, there are enough that you'll see progression throughout the game. With that said below you will find a list of enemies, at which cauldron you will meet them, and whether or not they are mountable.
PSI Cauldron
Watcher: Not Mountable
Strider: Mountable
Redeye Watcher: Not Mountable
Broadhead: Mountable
Charger: Mountable
Tallneck: Not Mountable
Sigma Cauldron
Grazer: Not Mountable
Scrapper: Not Mountable
Lancehorn: Not Mountable
Sawtooth: Not Mountable
RHO Cauldron
Longleg: Not Mountable
Trampler: Not Mountable
Shell-Walker: Not Mountable
Snapmaw: Not Mountable
XI Cauldron
Glinthawk: Not Mountable
Fire Bellowback: Not Mountable
Freeze Bellowback: Not Mountable
Zeta Cauldron
Rockbreaker: Not Mountable
Thunderjaw: Not Mountable
Stormbird: Not Mountable

Embark on an inspiring mission of human connection beyond the UCA. Sam — with companions by his side — sets out on a new journey to save humanity from extinction. Join them as they traverse a world beset by otherworldly enemies, obstacles and a haunting question: should we have connected?