Nebula, referred to as Potosu (ポトス) in the Japanese manual, is a badnik from 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 does 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 shooting in turns some spiked balls that can take down the player. Also appears in Sonic Runners as common enemies in the stage of power type. In addition they share both the design and pattern with Sonic Lost World ones, some just stand, hovering in the air. Appear in Sonic Runners Adventure in the same way as Sonic Runners.
In Sonic Forces, the Nebulas gain a new redesign to adapt to the badniks style of game, with a more militaristic and modernized look. Can be found in a variety of zones. In this game they can be found in a group and are totally stationary in the air, forming a Homing Attack chain.