Tankor is a Vehicon and a villain in the Beast Machines series, the sequel to Beast Wars.
When the Maximals returning to Cybertron from the Beast Wars were infected with Megatron's virus, Rhinox was not as lucky as most of his comrades. While the Transmetals were able to stay mobile for a time, Rhinox was immediately paralyzed and overtaken by the Tank Drones. His spark was forcibly removed and stored in a canister in Megatron's citadel.
When Megatron found that he needed underlings to properly control his Vehicon armies in battle, he used Rhinox's spark to power his tank general Tankor. He reasoned that if the Maximals discovered their new enemy had once been their close friend, they would be less willing to fight him. Unfortunately for Megatron, Tankor was only marginally more intelligent than the mindless drones he was created to lead. Meanwhile, Rhinox's spark remained intact inside Tankor, albeit unable to act.
The Maxies are playing with the big boys now! After Megatron claimed there were fabulous prizes to be won, for whichever general got the Maximals, Tankor went after them and, after a vicious battle, actually captured them. He then took them to Megatron and demanded his reward... which would be to have his spark removed. Primal managed to use his affinity with the Allspark to contact Tankor's spark and convince him to do the right thing: the Vehicon helped them escape and went on the run with then, but Megatron was able to remote delete the tank's memories of this so he'd be their enemy again. Primal felt something familiar about that spark though. The Maximals tried to ambush Tankor to see whether drones would stop functioning without their general; the plan would go tits up, however.
True to Megatron's expectations, the Maximals did attempt to reach Tankor's spark, and they discovered his true nature. They woke his spark, but the Rhinox they got was not the Rhinox they expected. Tainted and embittered by his time inside Tankor, Rhinox rejected the Maximals and embraced Megatron's plan for a "peaceful", technologically-pure Cybertron, only with himself at its head instead of Megatron. Don't make me pull this spark over.Tankor-Rhinox immediately began plotting against both Megatron and the Maximals. He caught and reprogrammed one of Megatron's Diagnostic Drones, forcing it to work for him.
Tankor found the Oracle and, using the Diagnostic Drone, retrieved the Key to Vector Sigma from within. He then faked his own death, seeking to remove himself from both factions' suspicions.
Manipulating events from behind the scenes, Tankor tricked Rattrap into activating an organic rapid-growth catalyst that would make the organics appear much more powerful and out of control, thus inspiring Megatron to take more radical measures to contain them.
His escalating arms race gambit worked in manipulating Megatron into firing the key on a planetary scale — which would have killed all the organics, including the Maximals and Megatron, leaving Tankor to rule a pure mechanical world. Tankor's manipulations failed when he tried to attack Megatron, and a provision against doing so, hard-wired into his programming, shut him down. Due to Tankor's manipulations, however, Primal opened the Plasma Energy Chamber and Megatron fired the Key. The ensuing clash of energies destroyed Tankor's body, and his spark joined the Matrix. Primal met Rhinox's spark one last time within the Matrix, where Rhinox expressed regret over his recent actions.
In the video game, Super Smash Bros. for Nintendo 3DS / Wii U, one of R.O.B.'s alternate costumes is based on Tankor's color scheme.