Flasher

is a firefly-type badnik created by Doctor Robotnik. It appears only at Mystic Cave Zone in Sonic the Hedgehog 2. Flasher has a small red head with two eyes and two antennae. The upper part of the body is black, while underside of its body has an electric bulb.

Description
Flashers usually appear floating on tunnels, as usually being on the player's way. When the bulb on its belly is not flashing, it is almost harmless. It periodically lights up its bulb, cloaking itself in electricity and temporarily making itself invulnerable. Flasher has the unusual ability of moving through walls.

Sonic the Comic
Flashers have made several appearances in Sonic the Comic as part of Robotnik's badnik army. Usually flying on swarms, these badniks are first seen in issue 23' story "Pirates of the Mystic Cave", where they are possible led by Captain Plunder. Flashers attacked against Sonic and Tails at Mystic Cave Zone, who are come to rescue Amy Rose from Plunder and apparently chose the wrong tunnel. They are unable to defeat Flashers while getting shocked and faint. Moments later, Sonic and Tails found themselves from Plunder's hideout.

Flashers later return in Sonic the Summer Special, where three of them were forcing Sonic to retreat, who almost fell down to a spike pit, but gets recurred by Tails in the last second. In issue 46' "Enter the Cybernik", Robotnik sends single Flasher to seal an Emerald Hill folk mouse in and then sent along with several badniks to capture more residents from to Emerald Hill Zone. It was quickly defeated by Shortfuse the Cybernik before even using its electrifying power.

Trivia

 * In Sonic CD, an enemy named Hotaru is similar to Flasher, as both being firefly-type badniks and able to electrocute target with its weaponry.
 * In its artwork as shown in Sonic Jam, Flasher's name is misspelled as "Frasher".