Masquerade was possibly the first WoD MU*, and likely the oldest still running if breaks and reboots aren't disqualifications — development began in late 1992, it opened in early 1993, and closed and opened again several times in the '90s. I believe the most recent reboot was in 2010, just before I joined the second time.

The game's set in Albuquerque, and currently allows various shifter types, vampires, mortals, and mortal+.  Come check it out!