The Meteor Head is a flying enemy that spawns only in the Meteor Biome. They often spawn in small groups around the Meteorite and will continue to spawn as long as over 50 blocks of Meteorite Ore are still intact. The easiest way to quickly stop Meteor Heads from spawning, is to destroy the Meteorite Ore with Dynamite.
The alternative way is to use a pickaxe for mining and fighting at the same time. Keep the meteor heads all on one side, face them, then start mining. The meteor heads will be struck by your pickaxe, whilst you're mining the Meteorite Ore. This can be done by identifying which side they are coming from, then jumping over the ones coming the other way. Another option is to play multiplayer mode and mine the Meteorite while another player attacks the meteor heads. Without using these methods mining meteorite can be very hard without good gear.
Due to the Meteor Heads' low health, they can be easily killed with higher-tier weapons, as well as farmed with a well-placed volley of Dart Traps.
An effective early-game weapon to use against Meteor Heads is the Vilethorn, because the weapon is unhindered by blocks.
In Multiplayer, Meteor Heads appear to spawn when one player is in the Meteorite Biome, affecting other players nearby.
In Multiplayer (If you're in a server with a bit of lag), Meteor Heads seem to teleport to the player who hit them; this is a client-side bug.
They seem to have a lower spawn rate when you are in a Meteor Biome which has landed in or next to the Ocean. This may be because, although they can travel through water, they perhaps won't spawn in it, ergo having the meteor near or in water reduces the number of directions Meteor Heads can come from.
It is possible to farm Meteor Heads for Meteorite, although it is a slow process due to their low drop rate.
In a Hard Mode world, Meteor Heads can be farmed for Souls of Light and Night if one places enough Meteorite Ore in an Underground Hallow or CorruptionBiome. This can be very useful as Meteor Heads are much weaker than the monsters normally encountered in these Biomes.