Skeletron is a Terraria pre-hardmode boss that resembles a skeleton head with two skeletal hands. Like most bosses, it can pass through blocks. Skeletron needs to be defeated to gain access to the Dungeon, and to allow the Clothier NPC to spawn.
Skeletron can be spawned by talking to the Old Man present at the entrance of the Dungeon at night. If talked to at day, the Old Man will simply deny and not allow you to activate his 'curse' to spawn Skeletron.
As mentioned above, Skeletron has a head resembling that of a Skeleton, and two large arms. If the player does not kill Skeletron before dawn, it will turn into the Dungeon Guardian and deal 1000 damage to the player and kill them.
Skeletron has two attacks-
- His head spins while his hands remain dormant.
- His head remains still, but his hands charge at the player.
When spinning, the head's defense is lowered from 10 to 0, but it's attack increases.
- Skeletron's Hardmode version is Skeletron Prime.
- Skeletron, unlike The Twins, or The Eye of Cthulhu, doesn't have a second form (unless you count the dungeon guardian)