Thoth was the arch enemy of the Martian Manhunter
A parasitic body-hopping neurological virus, Thoth possessed several different bodies. As Thoth communicated in thoughts, on Earth, he was always alone. One day he discovered the Martian race too communicated in thoughts. When he reached out to them, his infectuous and poisonous thoughts wiped out the entire race in a flurry of flames. When confronted by the Martian Manhunter, he opened up his thoughts to the last Martian and when his villainy was discovered, he was killed. However, Thoth merely moved on to a new body, as it was his host who had died, and vowed to take revenge on the Manhunter.