The most aggressive players in my eyes:
1. Montezuma - Declares war always despite of religion. Builds many off-troops, is annoyed when relations is
1+ or
0.
2. Ragnar - Builds much troops. Is often a small player, but has many troops, and declares war as mad. Often only not on the AIs, but the human.
3. Shaka - Declares war despite of the size. Once I has rifles, and 2500 points. One of my neighbours were Shaka, and he had 600 points, and he came with about 15 axes, swords or impis, and declared war.
4. Alexander - Is often pleased or friendly, but declares war despite of relations. He always build many troops.
5. Napoleon - He's often the biggest player or one of three biggest players (I always play with 11 AIs on huge map). He always build bunches of troops, and it's difficult to win a war against him. He often starts the wars early.
6. Genghis Khan - I've not played so many games with him, but he is a crazy warmonger. Sometimes he lives peacefully, but often he declares war on players that is much, much bigger, and loses the war.
7. Julius Caesar - He's not always a warmonger, but sometimes he has participated in many wars. He is often superior in the start, and declares war on players far away.
8. Stalin - He usually don't declare war on everyone, but he's very often a big player that has many vassals, and starts world wars. He has also declared war on players on other continents.
9. Hannibal - I've never seen him under the middle of the power rate. He's often one of the most powerful civs. I remember one time that he was crazier that Monty or Ragnar.
10. Pacal II - He's always annoyed or furious and looks . .. .. .. .ed up. I've rarely seen him playing peacely.