Dr. Shining Firefly (known as Shining Hotarunicus in Japan and Izzy Glow in the original American release) is a Reploid boss from Mega Man X5 that is based on a firefly. A Professor of Engineering from Japan, he was the world's leading authority on laser technology. He was also very reclusive and rarely shared his work with the outside world for fear that it would be used to manufacture weapons. The Maverick Hunters paid the good doctor a visit in the hopes of obtaining a key component for the Enigma Cannon, but Firefly had already been infected by the Sigma Virus and requested that the Hunters end him before he completely lost his sanity.
- Flight - Firefly's small, awkwardly-shaped body is ill-suited for walking and his wings are designed to be constantly active, so he never touches the ground during his battle.
- Teleportation - Firefly can make short-range teleport jumps to ambush his opponent.
- Prism Laser - Firefly fires a powerful laser beam from his tail and sweeps the room with it. He can sweep the laser across the floor or along the wall.
- Prism Shot - Firefly shoots eight balls of light along the floor, then absorbs them back into his body.
- Flash Laser - Firefly launches small insectoid drones that are charged with laser energy, leaving light trails in their wake. X can copy this weapon and Zero gains the Chaos Splasher Giga Attack based on Firefly's data.
Shining Firefly's body is poorly insulated against electric shocks, making him especially vulnerable to the Tri-Thunder and E-Blade. These attacks will short out Firefly's wings and cause him to drop out of the air.