#2 Piledriver (All variations)
There are many variations on the Piledriver. The most famous being the Tombstone Piledriver, which was used by The Undertaker for years. The Tombstone is probably the safest variation of the Piledriver, because most of the impact is on the knees of the person performing the move.
Owen Hart famously broke "Stone Cold" Steve Austin's neck with a Piledriver at SummerSlam 1997. The original plan was for Owen to hit a Tombstone Piledriver, but decided to hit The Hart Driver instead. Austin wasn't positioned properly and landed on the top of his head.
WWE banned the Piledriver in 2000 due to the dangers of it being botched. Wrestlers can only use the move with special permission. CM Punk reportedly defied this rule when he performed a Piledriver on John Cena, during a match on Raw in 2013.
The move is used a lot outside the WWE, and wrestlers take every precaution to perform the move safely.