Dino Piranha is a boss in Super Mario Galaxy and it is the first boss that Mario encounters. He makes his home in the Good Egg Galaxy. He is much bigger than his Super Mario Galaxy 2 counterpart Peewee Piranha. The Dino Piranha is inside an egg on his planet when Mario first encounters him. His egg is cracked when Mario crashes into him with the power of a Launch Star. The Dino Piranha then starts moving around from inside the egg, and when Mario attacks his tail, this will start a battle.
As his name applies, Dino Piranha is a cross between a Piranha Plant and a Dinosaur, Dino Piranha's head looks like that of Petey Piranha, though his body is much different. The Dino Piranha's body beneath the Piranha Plant head is that of a dinosaur's, with a green hue and has light green lips. His tail has a brown orb at the end of it with a texture like a seed. When he first breaks out of the egg his head is purple, but when enraged he turns red with anger, and when he is defeated it turns blue.
The Dino Piranha makes his first appearance when Mario smashes into his egg. The egg cracks a little and the boss's tail pops out. The bottom of the egg breaks open so Dino Piranha can move about while still in the egg. Mario must run to his tail as it is walking around and he must attack it by Star Spinning. This will cause his tail to fly back and smash the rest of the egg open. Dino Piranha is now fully revealed and starts running around the planet, initiating his second phase of the fight. Being the first boss, Dino Piranha is an extremely easy boss, Mario must use his Star Spin technique on the boss's tail in order to damage this boss, Dino Piranha mainly attacks by running around and attempt to deal contact damage on Mario/Luigi; be careful tho, as Dino Piranha gets damages, it becomes faster, after smacking its tail into it two more times, Dino Piranha turns a sickly color and explodes, releasing a Power Star.
- In the game's ending, Dino Piranha appears on the castle grounds next to a circle of Pumpkin Heads and Toads playing.
- The Dino Piranha makes a cameo appearance in Mario & Sonic at the London 2012 Olympic Games in the event Dream Spacewalk, making his home in the Sky Station Galaxy on the Geo Planet. The player must defeat him by passing through the rings to gain power. After his Stamina drops below half, the Dino Piranha will attempt to counterattack with fireballs.
- The theme music while fighting Dino Piranha is the same as while fighting Tarantox, even though the latter has the Boss Prelude theme which is usually applied to bosses with King Kaliente's theme.