Creeper Spawn Egg

History

Worked out by reading the registry of every Minecraft build Mojang has published, in release order.

Version	Date	What the files show
before 18w01a	—	Already in the game when Mojang’s data generator first shipped, in 18w01a (3 January 2018). The files do not say which earlier version added it.
18w20a	15 May 2018	Display name changed from “Spawn Creeper” to “Creeper Spawn Egg”.