The closest person we have had to a shooter on here was Tres Genco, and @Oedipus was his .is name (and he never ended up killing anyone, nor have I seen solidified proof that he was going to act upon his threats). Nothing else in this forum's 7 year, closing on 8 year history of being around with tens of thousands of users. If there were any other shooters or killers out of this forum, the media would have reported on it stat.
Also, Elliot Rodger used PUAhate, but that's all I know of.
The reason why you don't see any incel killers come out of these spaces, is because these spaces provide a good coping mechanism to those who are struggling as an incel. Incels here get more peace than they would if spaces like .is didn't exist. In a way, the sole existence of this forum for the period of time that it has been up for, with its lack of incel killers, is a massive counterargument to bluepilled retards and low IQ incel fearmongers trying to create a false narrative that spaces like this are dangerous. They just want to suppress our freedom of speech because they view women as the sole arbiters of morality, and radical feminism, misandry, and man-hatred is their field of worship.