- For the Toad Force V character from Mario Party Advance, see Jack (character).
- For the boss from Donkey Kong 64, see Mad Jack.
Jacks are an object originating from the Donkey Kong arcade game. Jacks are a variation of springboards found only in 75m, where they repeatedly enter from the upper-left area of the level around where Donkey Kong is, one after the other, and do two long bounces across the girder before falling straight down into a pit. If Mario gets hit by a Jack, he loses a life.
Jacks have seldomly appeared outside of Donkey Kong. However, in the Game Boy remake of the same name, if a Jack falls on Mario while he is doing a handstand, it falls off-screen.
They are also featured in the Super Smash Bros. series within the 75m stage, which first appeared in Super Smash Bros. Brawl. For this stage, Jacks act the same as in the original Donkey Kong, from which they had their behavior replicated. However, this is a stage feature that only occurs while the 8-bit Donkey Kong is not hiding within the background.