Wrestlers With The Most World Titles (Across All Major Federations)
1. Ric Flair (20)
10 NWA Championships
7 [8] WCW Championships
2 WWE Championships
1 [2] WCW International Championships
There was never any doubt about the man, only about the number of titles.
WWE get to their count of 16 world championships for Flair by acknowledging two WWE titles, six WCW titles and eight NWA titles. But wouldn't it be fairer to take into account what the involved promotions officially recognize(d) instead of simply following WWE's retroactive rundown ?
WCW billed Ric Flair as an eight-time holder of their main belt. In 1994, a match between Flair and Steamboat ended in a double pin and the title was vacated only for Flair to win it again. WWE never recognized the vacancy and Flair's additional reign, but WCW did. However, we can consider Flair a seven-time WCW champion as his first reign is a continuation of his 8th NWA title reign.
As for NWA, they consider Ric Flair a ten-time NWA Champion. During his 10th reign, WCW and NWA broke their business relations, and WCW thus renamed Flair the WCW International World Heavyweight Champion. His first WCW International title can therefore be considered a continuation of his 10th NWA championship reign. He would go on to win that title one more time by defeating Sting. WWE never acknowledged the WCW International title, but it was at the time presented by WCW as the equivalent of the NWA championship and labelled a world title. So that gets us to 20.
Flair himself has said he is a 21-time world champion. We guess that it's because he considers himself an 11-time NWA Champion, taking into account his win against Carlos Colon on 10 July 1983 in Miami, a title change that was never recognized by the NWA.