Reznor

Reznors are fire-breathing dinosaurs that made their first debut appearance in Super Mario World. According to the instruction manual, they were cursed by Bowser. They are bosses that Mario and Luigi fight in fortresses found everywhere on Dinosaur Land. They are now found in the Mushroom Kingdom since their next appearance in New Super Mario Bros. 2. Like how the Koopalings are named after various musicians, Reznors are named after Trent Reznor of the industrial rock band Nine Inch Nails. They are similar in appearance to the real dinosaur species, Triceratops.

Super Mario World
In Super Mario World, Reznors spit fireballs at the player. Mario must hit their platforms from below to defeat them. After two Reznors are knocked off their platforms, the floor breaks away, exposing the molten lava below. If the player does not defeat the rest of the Reznors promptly, they will have to jump onto one of the abandoned platforms and fight from there. It is, however, possible to defeat all four without doing so.

They are the bosses of the many fortresses scattered through the areas of Dinosaur Land; the Vanilla Fortress, the Forest Fortress, the Chocolate Fortress, and the Valley Fortress.

New Super Mario Bros. 2
Reznors appear in the Nintendo 3DS title, New Super Mario Bros. 2. They got little changes on their behavior and combat style from their debut, and their appearance hasn't changed either, although their chins have a lighter tone, unlike of Super Mario World that have an uniform color. This time in battle, the platforms they're standing on are the Rectangular Coin Blocks, which can be hit to gain three coins. After a short period of time, a Reznor roars, and the bridge Mario is standing on will start to collapse, much like in Super Mario World. Unlike in Super Mario World where four of them always appear on a single wheel, Reznors may also appear in pairs, one standing in the opposite side of the other on the wheel. Four of them and two wheels where a pair stands on each, or four of them standing in a single wheel with eight platforms. They are the bosses of towers, and the battle theme is a remix of the Super Mario World boss battle theme.

Super Mario Adventures
In Super Mario Adventures, several Reznors are shown to inhabit the basement of the Koopalings' Tower, attacking anyone who is dumped into the basement. These Reznor were apparently destroyed when, after attacking Princess Toadstool, Friendly Floyd, Mario, Luigi, Toad, and Yoshi, the Reznors ignited a bomb held by Princess Toadstool, blowing up the Koopalings' Tower.

Later in Super Mario Adventures, several Reznors, riding their spinning platforms, can be seen at Bowser's wedding to Princess Toadstool.

Super Mario-Kun
Reznors appear in the Super Mario World adaption of the Japanese manga, Super Mario-Kun. They attempt to spin very quickly in order that Mario and his friends cannot hit them, but due to the speed, they fall off their platforms, thus making Mario and his friends win the fight.