Edit
Glithor is a fused up Decepticon Machine came from Optimus Prime and Megatron from The Transformers
His Origins came from the Quintessons made with Cybertonium that is common for Transformers, he is a Decepticon. (despite being look alike from Optimus Prime)
From tfwiki:
The Colossal Cannon Soldier Gilthor (ギルトール Girutōru) is a bizarre, vicious fusion of Optimus Prime and Megatron, built by the Quintessons. Created from the same Cybertonium alloys which made Optimus Prime so resilient, and boasting a Destrogun many times more powerful than Megatron's fusion cannon, his combat power exceeds his predecessors' in nearly every way.
Gilthor, however, is ultimately a lifeless shell, animated by the ghost of Starscream, causing him to succumb to the same weaknesses as the Decepticon jet.
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