Grumpy Soldier is a fictional version of Sparta, a recurring boss enemy in the Roblox game Dummies vs Noobs. The fan wikis give him an age of 26 and say he was raised by monks in the remote Nusian mountains, where he trained with swords and was drafted for war in 2039.

Fans know him as a blazing-fast hunter with two blades and a jetpack who chases players down until they fight him. He is described as a high-ranking Noob Army specialist who works alongside Hermes and sees the Dummies as inferior targets. The game has little official biography for him, so this version draws its tone from how he acts on