Star Thwomp

Star Thwomps, also known as Super Thwomps, are a shiny version of Thwomps that appear only in the Mario Kart series, specifically.

Super Mario Kart
Super Thwomps first appear in Super Mario Kart on Rainbow Road where they act like regular Thwomps, though these Thwomps glow and spin racers out if they run into them, unlike normal Thwomps. There are sixteen of them, divided in four groups of four each, located after the first two ramps (two on each side), on the narrow straight after the next three ramps (two on the left side, then two on the right side), within the forked road (two per side), and before the finish line (in the center).

Mario Kart 7
Super Thwomps reappear in Mario Kart 7, with the return of as a retro track. Like before, they behave like normal Thwomps, but using their modern spiked appearance from New Super Mario Bros. Wii rather than the blunt one used by the Thwomps on Bowser's Castle. Once again, racers flip if they run into them. Due to their bigger size, they appear in lesser numbers, from sixteen to seven (one Thwomp stands in for every two originally present, though the second quartet is replaced with just one); they also cause the track to wave when they slam the ground, allowing racers to use them for tricks.

Mario Kart 8 / Mario Kart 8 Deluxe
Super Thwomps, here simply called Thwomps, appear once more in Mario Kart 8, once again on SNES Rainbow Road included in the first downloadable content pack. Unlike Mario Kart 7, they are based upon their Super Mario Galaxy design, much like the the Thwomps in Thwomp Ruins, though they still flip racers on contact. Along with the SNES Rainbow Road course, the Thwomps reappear in Mario Kart 8 Deluxe as part of the game's base content.

Mario Kart Tour
Star Thwomps return in Mario Kart Tour with their Mario Kart 8 and Mario Kart 8 Deluxe appearance and current name. They are found on SNES Rainbow Road, RMX Rainbow Road 1, and RMX Rainbow Road 2, functioning in the same manner as in previous installments. They are also featured as the obstacles in the Wario Cup's Glider Challenge in the Tokyo Tour (set in the same course) and the main obstacles in the Larry Cup's Steer Clear of Obstacles challenge in the Mario Bros. Tour (set in 3DS Rainbow Road), where they can also be seen staying still and moving horizontally as well.

Star Thwomps have also appeared in challenges outside of Rainbow Road courses: in the Steer Clear of Obstacles challenge in the Baby Daisy Cup of the Flower Tour (set in GBA Bowser's Castle 1), and the Glider challenge in the Larry Cup of the Peach Tour (set in SNES Mario Circuit 3).