The Days of Fear was an event in 6,000 BBY. During this time, a Dark Jedi, whose name was lost, killed over a thousand people in the Mid Rim. He was captured by Jedi knights who took him back to Coruscant to be executed. He escaped and three years were spent in fear of his attack. He was captured on the planet Vulpter and committed suicide.
Second Days of Fear[]
The unnamed Dark Jedi who began the Days of Fear.
In 100 ABY, another Jedi massacred many Mandalorians as a revenge act. He was driven insane by his crimes and drowned himself.