Ultima Online does not prohibit players from roleplaying evil characters, but it does ensure that evil in-game behavior is risky. Nonetheless, there are certain criminal types in the game that new players must be on the alert for.
Obviously, players who attack others with the intent to kill and rob them are a risk. If a player commits multiple murders he is flagged as a murderer, and highlights red when you pass your cursor over him. Murderers usually have a price on their head, which can be redeemed by taking the head to a town guard. (Use a bladed weapon on the body to take the head – caution, this action will have some negative impact on your Karma … bounty hunting is not the most respectable pastime around.)
Professional thievery is an ancient fantasy tradition, and there are players who will cheerfully lighten your purse for you. The best way to avoid thieves is to stay out of crowds and don’t let strangers stand too close. It also helps to keep moving and go into war mode (but be careful about accidentally attacking someone, which will flag you as a criminal.) A thief whose attempt to steal is detected is flagged as a criminal for several minutes. A criminal highlights gray, and can be attacked by all passers-by without having to worry about losing Karma.
Looting is robbing the dead. If you attempt to remove items from the corpse of a PC before the corpse deteriorates, you are looting and will be flagged as a criminal for the next several minutes. The only exception is members of the same adventuring guild as the deceased, who can collect the possessions of dead guildmates immediate for later return.
There are other behaviors which, while not actually penalized by the game itself, are considered rude and immature, and will make you intensely unpopular among other players. These include:
Stepping in to administer the killing blow to a monster (and grab the associated Karma and Fame bonuses) when others have done most of the fighting.
Stepping in to grab all the treasure from a dead monster when others have borne or shared the risk of fighting it.
Scams, including inflating the price or misrepresenting the value of trade goods
