#1 Triple H never defeated Roman Reigns
Triple H first crossed paths with Roman Reigns when he tried to recruit Seth Rollins to The Authority. While The King of Kings succeeded with Rollins, he got on Reigns' bad side. A few years later when he tried to bring Reigns to his side, the former world champion was met with disappointment.
The Cerebral Assassin couldn't digest the rejection and sought revenge on The Big Dog. Reigns defended his WWE Championship against 30-men. in the 2016 Royal Rumble match. Triple H made a surprise entry at no. 30 and eliminated Reigns and Dean Ambrose to win the match as well as the WWE Championship.
Reigns regained the gold at WrestleMania 32 when The Big Dog defeated The King of Kings to become the new WWE Champion. That was the last time the two men were involved in a one-on-one match.
Since then, he and Reigns have crossed paths only once. On August 29, 2016 edition of RAW, The Cerebral Assassin made a return and attacked Reigns and other stars to help Kevin Owens become the Universal Champion.
Nonetheless, Reigns isn't the only star against whom the world champion has never scored a pinfall victory. Seth Rollins' name is also included in that short list.