Tal
which grandmaster played the most aggressive chess?

What does the word "aggressive" really mean? A master like Korchnoi who grabs a pawn and dares you to try and do anything about it it pretty damned aggressive. A master like Karpov who tries to lay claim to every square on the board and squeeze you to death is pretty aggressive too. Aggressiveness is not just a matter of sacrifices
I'd be curious as to which 2700+ GM and/or WC has the lowest draw percentage as Black.

Paul Morphy maybe?
Even Alekhine?!
Although, Garry Kasparov was patient with his openings then extremely aggressive in his middle & endgames.
I'd say Paul Morphy.

Those are some interesting graphs!
You could win a few bets with chess players if you asked who had the highest draw rate between Giri, Aronian and Ivanchuk!

Nezhmetdinov lost some ridiculous games though, especially to Averbakh. He was probably the most aggressive, but his tactics were often unsound.
In terms of the most dangerous opponent, the one a GM could lose to in any position, it's either Kasparov or Carlsen.

gone were the days of kasparov, tal and others. i think in today's time Carlsen play aggressive after midgame . till midgame he is kind of defensive. Ian play good attack , Mvl as well as Hikaru and Giri . yes giri play chess agressively at the very begining however i see him flinched many time to take a call . he may be have some fear or a habit of making blunders in the mid and end games and instead of winning compromise with a draw or loss. Hikaru was my faviroite because the way he misses . he always one or 2 step behind making checkmate and all the time the opponent just got luckier .carlsen had been lucky against "HIKARU,NEPO,AND GIRI" .
Tal, and player who loved Tal's style, like Simon Williams (aka the Ginger GM)