The chess piece that can castle is the king, and it does so together with one rook in a single special move.

What castling actually is

Castling is a special move where two pieces move at once: the king and one rook.

The king moves two squares toward the rook, and the rook jumps over the king to the square next to it.

There are two types of castling:

  • Kingside castling (short castling), written as O−OO-OO−O.
  • Queenside castling (long castling), written as O−O−OO-O-OO−O−O.

So when someone asks “the chess piece that can castle,” they usually mean:

  • The king , which is the piece that initiates the castling move.
  • But note: the rook involved in the move also moves as part of castling.

Conditions for castling

For castling to be legal, all of the following must be true:

  • The king has not moved earlier in the game.
  • The rook you are castling with has not moved earlier in the game.
  • All squares between the king and that rook are empty.
  • The king is not currently in check.
  • The king does not pass through a square that is attacked.
  • The king does not end up on a square that is attacked.

An example: for White kingside castling, the king goes from e1 to g1 and the rook from h1 to f1, assuming all conditions above are met.

Quick forum-style take

In standard chess, only the king “can castle,” and it does so together with a rook in one special move. If either the king or that rook has moved, you’ve lost castling rights on that side.

TL;DR: The chess piece that can castle is the king , and the move also involves one rook as part of the same special move.

Information gathered from public forums or data available on the internet and portrayed here.