P.L.A. Mecha and Optimus Prime

Based on the mechs from several Transformers comics (see link), the P.L.A. Mecha is a human-designed mobile strike vehicle built around the frame of a Chinese attack jet. It is enhanced with the ability to transform into a bipedal mech armed with an autocannon and the missile launchers from the jet mode.

Despite its great potential, production was discontinued after the majority of the mecha were destroyed during a fight against both the Autobots and the Decepticons, leaving only a few surviving in various airbases. However, various governments have invested in such machines, especially ones built using ground vehicle frames, as those can afford increased armor and weaponry.