A Black Hole is a very dangerous object found in the Mario series. They are based off the the real-world black hole. Their first appearance is in the Mario Party 6 mini-game Black Hole Boogie and they appear again in Super Mario Galaxy and its sequel.
Black Holes have a much greater role in Super Mario Galaxy and Super Mario Galaxy 2, where they act as an obstacle which can suck Mario (or Luigi) into it if they are within its vicinity. Mario or Luigi can only be sucked into one if he falls off some ledges or misses the desired target when using a Sling Pod or Cannon. If either one of the plumbers is sucked into a Black Hole, his Health Meter is instantly be reduced to zero and he loses a life. Black Holes are usually impossible to avoid once the player has fallen off a platform and into outer space, though this obviously does not apply if Mario is in possession of a power-up that grants him the power of flight, or something along those lines, such as the Bee Mushroom, the Boo Mushroom, or the Cloud Flower. They are, in a way, the equivalent of bottomless pits found in most other Mario series platformers.
However, Mario or Luigi can also use Black Holes to their advantage. For example, any enemies or objects that fall into a Black Hole are destroyed after falling a certain distance toward it, so Black Holes can sometimes be used to destroy certain enemies in various areas. Note that any enemies destroyed by falling into Black Holes do not yield any items whatsoever. Likewise, any items that do get released by enemies that are destroyed while over a Black Hole are quickly enveloped by the Black Hole and removed as well. In some cases, Black Holes transform into a Power Star after a certain task has been completed. Mario or Luigi are then pulled to the Power Star by gravity in the same way as with the Black Hole with a red line. If Bee Mario is sucked into a Black Hole he will leave a yellow line. If Cloud Mario is sucked into a Black Hole, he will leave a white line.
At the end of the game, after Mario has defeated Bowser for the final time, his gigantic sun collapses into a massive Black Hole, which will quickly begin to engulf Mario, Princess Peach, Bowser's entire fleet of Airships, Princess Peach's Castle and the Comet Observatory. Just as everything is about to be destroyed, Luma suddenly appears in front of Mario, waves at him and then sacrifices himself by throwing himself into the Black Hole. Thousands of other Lumas soon join him in flinging themselves into the massive Black Hole in hopes of stabilizing it and ultimately saving the universe from destruction. Eventually, the Black Hole twists wildly around in space before finally exploding in a new "big bang", thereby reforming the entire cosmos and creating an entirely new galaxy, which Mario is welcomed by in the final cutscene of the game. Also, in Super Mario Galaxy 2, Bowser is sucked into a Black Hole when transitioning to his third phase and again upon defeat.
Another black hole appears in Mario Party 9, in the background of the final boss mini-game, Bowser's Block Battle. It seems to suck in large planets, and also Mini Stars. When the players defeat Bowser, the Koopa King once again stumbles into the black hole, although in the final cutscene, it is shown that Bowser and Bowser Jr. can normally fly inside the black hole with their Koopa Clown Cars.
Black Holes can come in different sizes in Super Mario Galaxy and in Super Mario Galaxy 2. Some small black holes can be really massive, like the black hole in Space Junk Galaxy in the Silver Stars area in Super Mario Galaxy. Same with large black holes, they can be massive or not massive.
- Bowser is actually sucked into a Black Hole twice himself: once after Mario defeats him for the first time in the final battle of Super Mario Galaxy 2, another time after Mario defeats him for the second time during the same battle (though the second Black Hole seems to be slightly larger than the first, and also sucks up the background with it). Princess Peach and the final Grand Star are shot out of the remains of the Black Hole several seconds later. And finally a third time when defeated in Mario Party 9s Bowser Block Battle mini-game.
- In real life, a Black Hole is what remains of a large, heavy star if it collapses upon itself following a supernova explosion; its force of gravity is so strong that not even light can escape.
- For some reason, in galaxies with the Star Ball, if the player falls into the black hole, it will not suck the player in. This may be because Star Balls are too large in their intact state.