Meteor Head

They come with the ore, not with the location. Enough Meteorite in one place makes the area count as a meteorite biome, and from then on nothing else spawns there apart from at the ocean, so a crash site is a sealed room containing exactly one enemy. They drift toward you through solid rock, slowly and without stopping, which means the tunnel you are digging protects you not at all. Touching you is the whole attack, it hits far harder than anything else you have met by that point in a run, and there is a good chance of it setting you on fire as well.

The real question is whether you can keep swinging the pickaxe. An Obsidian Skull stops the ore itself burning you and a Cobalt Shield stops the knockback shoving you off your dig, and combining the two into an Obsidian Shield buys both effects for one slot. A grappling hook does the anchoring half for free if you have nothing better. Because they close so slowly you can work in rounds: mine until a few of them are on screen, clear the screen, go back to mining. In multiplayer, split the jobs and let someone else swing at them.

Anything that only hits what it can see wastes most of its swings, since they arrive through the rock rather than down the tunnel. The Vilethorn is the standout because it ticks along its whole length regardless of terrain, and a spear like the Dark Lance does a narrower version of the same job. If you already have that tier of gear, a Night's Edge or a musket removes one per hit and the problem stops existing. Minions and the Crimson Rod will handle them without you looking up from the ore.

Mine the site down far enough and the area stops qualifying, the heads stop spawning, and the last stretch of ore comes out in peace. The rule runs backward too. Stack up enough meteorite anywhere you want and you have built a spawner that overrides whatever that place would normally produce.

• They rarely drop a block of the ore, which technically makes it renewable. Farming them for it is a waste of an evening: killing your world evil boss again drops a fresh meteor and is faster by a wide margin.
• They deal more damage than their own maximum health, a club with only the small bee and the Servant of Cthulhu in it.
• Their sprite is the old meteorite ore texture with a face on it.