Nebula, called Potosu (ポトス) in the Japanese manual, is a Badnik from the 16-bit version of Sonic the Hedgehog 2 found in Sky Chase Zone. It is an armored Badnik with a yellow propeller which hovers in midair, then rises to drop a bomb under itself when approached. Hit it anywhere to get rid of it.
The enemy reappeared in Sonic Pocket Adventure's Sky Chase Zone.
Nebulas return again in Sonic Lost World, where they receive an adapted cartoons redesign as well as other Badniks in the game. In this game they usually fly in groups or chains, but unlike their previous appearances, they do not shoot spiked balls through their cannons and can appear as obstacles in rails. They can be found in Tropical Coast Zone 3 and Zone ?, Lava Mountain Zone 2 and Hidden World Zone 2.
They reappear in Sonic Jump Fever's Blue Sky Zone as one of the zone Badniks, with their original pattern of dropping spiked balls that can take down the player. They also appeared in Sonic Runners as common enemies in Lava Mountain, sharing the design with the ones in Sonic Lost World. Some are stationary, hovering in the air. They have also appeared in Sonic Runners Adventure in the same way as Sonic Runners.
In Sonic Forces, the Nebulas gain a new redesign to adapt to the more militaristic and modernized look of Eggman's army. They can be found in groups a variety of zones, remaining totally stationary in the air in groups, forming a Homing Attack chain.
A variant of Nebula, known as Cactula, appears in Sonic Mania's Mirage Saloon Zone.