| Metal Knuckles
| First seen: Sonic R (1997)
| Species: Robot
| Gender: None (attributed as Male)
| Height: 110 cm (3'7")*
- Not to be confused with Mecha Knuckles of Sonic Advance or from the Archie series.
Metal Knuckles is an artificial copy of Knuckles the Echidna created by Dr. Eggman, and appears as an unlockable character in Sonic R. Much like Metal Sonic, Metal Knuckles was created with the intention that it would destroy its biological counterpart.
Sonic Channel featured Japanese language profiles of the Sonic R characters; translated, Metal Knuckles' is as follows:
As with Sonic, Eggman prepared this secret weapon for the sake of overthrowing Knuckles, considering his existence to be a hindrance. Having the same power plant as Metal Sonic, speed and acceleration power are high, but like Knuckles, this robot can glide from high places.
[Appearance requirements] Collect 5 tokens in Reactive Factory in Grand Prix mode and finish better than fourth place to begin a one-on-one match with Metal Knuckles. Win this race and Metal Knuckles will become a possible choice on the character select screen.
- Low turning ability. To turn without losing control, you must decelerate.
- Due to inertia, traveling on water is possible. Falling in the water may cause Metal Knuckles to become confused.
- From a high place, aim at a shortcut without pausing.
— Sonic Channel
Metal Knuckles is often cited as the second-best racer in Sonic R, consistently beaten only by Super Sonic. Along with Metal Sonic and Tails Doll, Metal Knuckles completes Sonic R's set of artificial copies for Team Sonic. The robot's debut is his only appearance to date.
- While Metal Knuckles has no listed height data, he is likely the same height as his organic counterpart. This is based on the fact that both Sonic and Metal Sonic have a shared height, and the classic heights of both of those characters have been retconned to match the modern ones.
| Characters in the Sonic the Hedgehog game series
||Sonic (Super, Hyper, Darkspine, the Werehog, Excalibur) | Tails (Super) | Knuckles (Super, Hyper) | Amy Rose | Cream | Big | Blaze (Burning) | Emerl | Silver (Super) | Marine | Lumina Flowlight | Chip | Shahra | Knights of the Round Table | Caliburn | Yacker | Sticks | Avatar
||Shadow (Super) | Rouge | Espio | Charmy | Vector | Mighty (Super) | Ray (Super) | Chaos (Perfect) | E-102 Gamma | E-123 Omega | Bean | Bark | Jet | Wave | Storm | Shade | Merlina
||Dr. Eggman | Metal Sonic (Rocket, Neo, 3.0) | Mecha Sonic (Super) | Fang | Witchcart | Battle Kukku Army (15th, 16th, Dr. Fukurokov) | Tails Doll | Metal Knuckles | E-Series | ZERO | Void | Biolizard | G-merl | Eggman Nega | Black Doom | Shugo-hei | Iblis | Mephiles | Solaris | Erazor Djinn | Captain Whisker | Johnny | Master Core: ABIS | Ix (Super) | Dark Gaia | King Arthur | Orbot | Cubot | Deadly Six (Zavok, Zazz, Zomom, Master Zik, Zeena, Zor) | Hard Boiled Heavies | Infinite
|| Sonic/Heroes | Rose | Dark | Chaotix | Babylon
|| Gerald & Maria Robotnik | Froggy | Chao (Hero, Dark) | Omochao | Cheese | Chocola | Vanilla | Tikal | Pachacamac | E-101 Beta | Illumina | President | G.U.N. Commander | Elise | Duke of Soleanna | Coconut Crew | Vikings | Professor Pickle | Wentos | Don Fachio | Dodon Pa | Heavy and Bomb | Tiara Boobowski | Honey | Flicky | Animals | Wisps