ECW started out as Eastern Championship Wrestling, an independent promotion out of Philadelphia in 1992. In August, 1994 ECW was renamed Extreme Championship Wrestling, and started to recognize their Heavyweight and Tag Team Champions as "World Champions" and on the very first ECW on TNN Show in 1999, they started out their World Champions video package with Shane Douglas after he droped the NWA World Title belt down after his win over 2 Cold Scorpio and declared himself the first "ECW World Champion" and ECW withdrew from the NWA. However instead of having two listings, one for Eastern Championship Wrestling heavyweight Champions, and one for ECW World Champions, its much more easier just to list all champions under the one listing
World Champions
World Tag Team Champions
TV Champions