Rocket launcher/Doom 3

The rocket launcher of Doom 3 is a powerful weapon that is first found halfway through the single-player campaign. It carries highly-explosive rockets and reloads quickly. Although it provides little boost for the player in single-player, it can be used for rocket jumping in multiplayer.

I would recommend not wasting rocket ammo on zombies or imps. Save it for booses and tough demons, like mancubi and hell knights. If you use rockets on the weak, you will be screwed when you find a tough enemy. hint hint.