The Void Gear (ヴォイドギア Voido Gia?) is Vanitas's Keyblade, and a Keychain for Terra's, Ventus's, and Aqua's Keyblades, and appears in Kingdom Hearts Birth by Sleep, Kingdom Hearts Birth by Sleep Final Mix, and Kingdom Hearts III. Vanitas is able to wield this weapon because he is the embodiment of fellow Keyblade wielder Ventus's darkness.Vanitas Remnant wields a monochrome version of the Void Gear.
Vanitas's Void Gear has numerous similarities to his Master's Keyblade. The teeth and head are black with a red outline and possesses a round, cog-like shape. The handle is red and the guard has the same coloration and cog-like shape as the teeth. The shaft is predominantly colored in shades of grey and sports a copper-colored gear in the center, with two intersecting, black chains wrapped around it. Two more chains are wrapped around the base of the shaft in a similar fashion.
It also has two blue, reptilian eyes, like the Soul Eater, Way to the Dawn, Chaos Ripper, and Master Xehanort's Keyblade; one located in the head of the blade and one embedded in the hilt. Its Keychain is comprised of three small, copper gears and ends in a charm resembling two halves of a gear arranged in an S-shape.
Vanitas Remnant wields its own, monochrome version of Void Gear. Its design is identical, save for the color scheme. The guard and teeth of the Keyblade, as well as the chain wrapped around its shaft, are all black. Its shaft is white and the two eyes on it are grey. The Keychain and token are also grey.
The Void Gear's name references the gears and cogs that make up its design, as well as Vanitas's own name, which means "emptiness" in Latin. Fittingly, the weapon's German name is "Clavis Vanitatum" which means "key of vanities" in Latin. In the French version, it is called "Clavis Vacuum", literally "Key of Void".