Cotton Mather may not have had a direct hand in the Salem trials, but as I recall he was practically a cheerleader at the execution of his Harvard classmate Rev. George Burroughs.
True -- although I'm not sure that "cheerleader" quite captured what Mather did.
Burroughs flawlessly recited the Lord's Prayer, something that someone who had sold their soul to the devil wasn't supposed to be able to do. Mather gave a short speech saying something to the effect that people should have faith in the magistrates and the court that pronounced guilt. Though Mather had not witnessed the proceedings, most of the others there to see the hanging had, and based on what they had seen in the courtroom, they were satisfied that Burroughs was guilty.
One of the more interesting aspects of the Salem trials, and New England witchcraft trials in general, is the extent to which laymen felt betrayed by courts that rendered "not guilty" verdicts (something they did something like 80 percent of the time). Mather's appeal to the correctness of the verdict -- when most men knew that most courts were reluctant to condemn witches to death -- must have struck a reassuring chord. Whether or not that's cheerleading -- well, I suppose that's in the eye of the beholder.