1. The Kid
2. The Gloat
Magic is a weirdly personal game in that it is almost exclusively a one on one affair. Like there were rules for dueling in ye olden times, there are rules for dueling in Magic. It is doubtful that Aaron Burr pumped his fist and shouted OH YEAH after plugging Alexander Hamilton. When playing Magic, be Aaron Burr.
3. The Stonewall
Magic is supposed to be a fun, social game but you wouldn't know it from the way The Stonewall goes about their business. The most information you can get out of them is a cursory grunt and to make eye contact with you would be a capital crime. Playing the Stonewall is about as much fun as playing Solitaire by yourself on a beautiful spring day.
4. The Newbie
Chances are that this person is you or was once you many moons ago. They don't have the cards memorized, they are a little off on the etiquette and have not figured out the nuances of the game. DO NOT BE A JERK. When confronted with a Newbie, there is a natural inclination to turn into one of the other players on this list. Resist the inclination and help them learn the game. Your karma will be rewarded with a good draw somewhere down the line.
5. The Speed Demon
The Speed Demon is the bane of the new tournament player in that they refuse to announce what they are doing, they just attempt to do it quickly enough to shock and awe you into submission. They announce spells and immediately try and announce the result, tap their fingers impatiently while you take your turn and generally try to rip through a game as quickly as possible. Ignore the blitzkrieg and take your time, chances are your ability to slow down the game will force them into mistakes.