Which Mario Party 7 unlockable character is a skeletal Koopa?

The Mario Party 7 unlockable character who is a skeletal Koopa is Dry Bones.

Dry Bones is the undead, skeleton-like counterpart to the standard Koopa Troopa. In Mario Party 7, released for the Nintendo GameCube in 2005, Dry Bones and Birdo are the two unlockable playable characters. Both joined the Mario Party roster in this installment.

The character is easy to confuse with Koopa Kid, who appears in Mario Party 7 as a non-playable character involved in board events. Hammer Bro and Boo are also Mario characters, but neither is the skeletal Koopa unlockable described here. Dry Bones later became a recurring playable character in other Mario spin-offs, including Mario Kart and additional Mario Party games.

His design comes from the broader Mario enemy family: Dry Bones are reanimated Koopa-like creatures that can often collapse into bones and recover after being defeated. That undead ability, rather than a special Mario Party role, is what gives the character his name and visual identity.