type T personality
n. A personality type that regularly seeks out thrilling or dangerous experiences.
Examples
2002
I used to skydive off buildings in south county. I've climbed most of the peaks in the Southern California, like Mount Baldy and Mount Whitney. I like to climb them when they're covered with snow. I need the rush. I need the endorphins. I'm a type T personality: thrill seeker.
—Gary Copeland, “Who's this?,” Orange County Register, November 08, 2002
1985 (earliest)
Comedian John Belushi. Gangster John Dillinger. Nobel Biologist Francis Crick. All are classic Type T personalities, and so, fittingly enough, is television's Mr. T.

As Psychologist Frank Farley of the University of Wisconsin tells it, many of the world's daredevils, doers and delinquents share a common personality, Type T (for thrill seeking). Whether scientists or criminals, mountain climbers or hot-dog skiers, says Farley, all are driven by temperament, and perhaps biology, to a life of constant stimulation and risk taking. Both the socially useful and the socially appalling Type Ts, he says, "are rejecting the strictures, the laws, the regulations — they are pursuing the unknown, the uncertain."
—John Leo, “Looking for a Life of Thrills,” Time Magazine, April 15, 1985
Notes
We all know the classic type A personality, which was identified in 1959 by the cardiologists Meyer Friedman and Ray Rosenman. But there's a whole type taxonomy out there, of which today's type T personality is but one example. Here's a list of all the personality types I was able to identify (note that many of these require your tongue to be planted relatively securely in the cheek of your choice):

Type A - Competitive, driven, stressed, workaholic.
Type B - Relaxed, patient, friendly.
Type C - Reticent, unassertive, nice to a fault.
Type D - Anxious, insecure, gloomy, depressed.
Type E - High-achieving, perfectionist, everything to everybody.
Type F - Prone to forwarding e-mail messages.
Type H - Hostile, hateful.
Type I - Egocentric.
Type J - Orderly, neat.
Type M - Melodramatic.
Type O - Prone to making spelling mistakes.
Type P - Persistent.
Type R - Responsive.
Type S - Doesn't get enough sleep.
Type T - Thrill-seeking.
Type V - Plain, simple (vanilla).
Type W - Wacko.
Type X - Domineering, tyrannical.
Type Z - Extremely laid back (the "opposite" of a type A).