Thwomp

Thwomp is a large stone block that is usually covered in spikes said to be possessed by a Boo. They are either Blue or Gray and have an angry face. They first appeared in Super Mario Bros. 3 and tried to squish Mario whenever he walked underneath them. They have also been in Super Mario World, Super Mario Kart, Super Mario RPG, Super Mario 64, Mario Kart 64, Mario Party, Paper Mario: The Thousand-Year Door, Mario Kart: Double Dash!! and Mario Kart DS.

In Super Mario RPG, Thwomps act as obstacles and cannot be fought like normal enemies. A Thwomp would attempt to crush Mario if he walked by, knocking the plumber unconscious for a short period of time. Additionally, if Mario is standing on a staircase and Thwomp crashes to the ground, the plumber will tumble backwards down the stairs. Thus Mario must jump up the staircase quickly before Thwomp has a chance to strike. Interestingly, one Thwomp that lives in Booster Tower rests on a teeter-totter. When Mario hops on the other end, the Thwomp will fly up, smash its own end, and send Mario soaring high up in the air.

Variations

 * Thwimps: Small versions of Thwomps found only in Super Mario World. They jump from side to side.

Minor Thwomps

 * Mrs. Thwomp: A female Thwomp. She is married to Mr. Thwomp. She is always very angry.
 * Mr. Thwomp: Mrs. Thwomp's calm husband.

Mario Superstar Baseball
A few Thwomps appeared in Mario Superstar Baseball as obstacle in Koopa Castle (once it's unlocked.) They try to keep anyone from scoring a homerun. They also appear in the unlockable minigame Stardash and try to smash anyone who is beneath them. If anyone gets smashed by them they will lose some of their coins.