What are some of the most aggressive chess openings?

Scotch

One of the most aggresive

Basic Colle +C4. Black can't have a closed position and often leads to a quick end game.

yes, that was just 1400 me not knowing what he was talking about two months ago

     The Saemisch King's Indian does give white strong attacking chances when they castle queenside, but it also gives black strong attacking chances as it is easy to open queenside files for the major pieces to combine with the fianchettoed bishop. It's a case of whose attack breaks through first.

     But the MOST aggressive openings are those where one side commits everything to a do-or-die attack. Marginally unsound ideas that lead to losing endings unless the attacker mates or wins decisive material. Things like the Evans Gambit, where the refutation is known but the attacker just wants a lasting initiative, and to keep all the attacking chances to themselves. In the King's Indian, the Four Pawns Attack fits this description better than the Saemisch.

     Of course, such super-aggressive all-or-nothing attacks don't work out well at the highest levels, where the opponent will be capable of deflecting the attack, but for the rest of us they can lead to exciting, entertaining games. They also often lead to lost rating points.

For a second there when I read this I thought I was reading one of my old account excellent point