The Hook Mate

The HOOK MATE is a four-part machine:

1. A ROOK delivers the check 2. A KNIGHT protects the rook 3. A PAWN protects the knight 4. An ENEMY pawn blocks the king's last flight square

The shape looks like a hook — rook at the tip, knight and pawn curling behind it. It appears constantly in endgames where a rook and knight hunt an exposed king.