Roy Koopa

Roy Koopa is presumably the third oldest of the seven Koopalings, the seven kids of Bowser who appear in several Mario games.

Super Mario Bros. 3
Roy is the fifth Koopaling to be fought. He is encountered in an airship at Sky Land. His fighting style consists of trying to crush his opponents with ground shaking stomps. Once defeated, he runs off, leaving behind the wand he used to transform the king of Sky Land.

Super Mario World
Again, Roy is the fifth Koopaling to be fought. He is fought in a room where the walls are steadily closing in, and often comes onto the ceiling. His attack style is simliar to that of his brother Morton. To defeat him, as in Super Mario Bros. 3, Mario must jump on him three times. Once defeated, he spiraled into the distance and exploded in a cloud of smoke.

Mario & Luigi: Superstar Saga
Roy returned in Mario & Luigi: Superstar Saga, working for Bowletta in Bowser's castle. As usual, he is the fifth Koopaling to be fought. Once defeated, he apparently dies like the others, and vanishes.

Super Princess Peach
Although not actually seen in the game it was revealed that Roy along with his other siblings(excluding Bowser Jr.) were to make an appearence in this game but were taken out for no apparent reason. Every one of the Koopalings had their own complete sprite sheet.

New Super Mario Bros. Wii
Roy reappeared in New Super Mario Bros. Wii. This time, he is the second Koopaling to be fought. Like the others, he is fought twice per level. The second time he is fought, Kamek casts a spell making the battle reminescent to Larry's from Super Mario Bros. 3. Once defeated, Roy fell off the screen, but survived, as he was seen alongside Bowser, Bowser Jr., and the other Koopalings, before Bowser's castle fell on top of them and crushed them.

Physical appearance
Roy is a muscular Koopa. He is always shown wearing a pair of red sunglasses, which obscures his eyes in the games, though in The Adventures of Super Mario Bros. 3 and the Super Mario World cartoon, his small eyes are visible through the lenses of his sunglasses. Like Wendy, he originally had a pink shell. However, in New Super Mario Bros. Wii, his shell is a shade of purple. He has a pink head, and is the only Koopaling to have one. His unused sprite for Super Princess Peach bears a green shell, and an orange head. Like most of the Koopalings he has visible fangs in the corners of his mouth; they are bigger than his siblings' fangs.

Trivia

 * Roy's name is derived from Roy Orbison.