Besides undertaker or kane has anybody else done a tombstone?

Yes. Taker did not invent the move, but it's who the move is most ociated with. Don Muraco used a tombstone as his finisher long before anyone even knew who The Undertaker was. He never called it a tombstone, that name came with Undertaker, but the move was around long before Taker even started wrestling. It was used as an illegal piledriver in Mexico for years. In Mexico it's called El Martinente. Owen Hart also had a variation of the move (it was the move that he broke Stone Cold Steve Austin's neck with)