The Death Ball (デスボール Desubōru?) is a sub-boss from Sonic & Knuckles, as well as its locked-on form, Sonic the Hedgehog 3 & Knuckles. Under normal gameplay, it is encountered in Death Egg Zone Act 2 when playing as Sonic (and/or Tails in Sonic 3 & Knuckles).
The Death Ball floats from side to side between the two anti-gravity devices. Sonic or Tails can use to reverse gravity. The yellow bumper shield(s) always positions themselves between the Death Ball and the player, making it impossible to be damaged directly.
The only means the Death Ball has of attacking is by way of strange buggy-like objects that it drops from its mouth on its underside. These have wheels on the bottom and spikes on the top. If gravity is normal (so objects fall downwards) they will move around on their wheels, but if gravity is reversed, they will become lodged on the ceiling and not move at all. They explode after a delay of about twenty seconds by releasing the three spikes in different directions.
The player must cause the spiked buggies to accumulate on the floor, then enter one of the anti-gravity devices to reverse gravity and have the character walk about on the ceiling. A Spin Dash is then required to throw the buggies off of the ceiling. If one hits the Death Ball, a hit is scored, otherwise the spiked buggy will move along the ceiling. A hit is also scored if a buggy "falls" between the surface and hits the Death Ball spike-first along the way. Eight hits are required for it to be destroyed.
- If the Level Select code is enabled in Sonic the Hedgehog 3 & Knuckles, it is possible for Knuckles to play through the Act and fight this boss.
- Super Tails proves to be a hindrance against this boss - the super transformed Flickies will destroy the buggies necessary to damage Death Ball, and are unable to damage it themselves.
- Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 56. ISBN 978-1506719276. "Bosses: Act 2 - Death Ball. Its orbiting shields can't be damaged. Use the shifting gravity to use its own deployed mine tanks against it."
- (in Japanese) ソニックメガコレクション最強攻略ガイド. Shogakukan. 1 March 2003. p. 189. ISBN 978-4091060907.