A black hole is an astronomical feature that occurs when a massive star collapses into an extremely small singularity so dense than not even light can escape its gravatational field. The "event horizon" is the area around the core at which point it becomes impossible to escape the gravitational pull.
Transformers have encountered black holes on a number of occasions and they have frequently been shown to function as portals between alternate universes.
- A Quintesson ship with captured Autobots and Decepticons aboard passed through one to a universe where the color spectrum was reversed.
- The bounty hunter Axer traveled through one from the Generation One continuity to the Robots in Disguise continuity.
- In the Unicron Trilogy, Unicron's destruction created an especially large black hole which threatened to destroy the multiverse.