Won't say better but some other records:
Don Bradman test average 99.94 (almost double that of 2nd best of his era)
West Indies undefeated streak in test series for 15 years till 1995
Usain Bolt, Michael Phelps records especially in Olympics
Aleksandr Karelin the Greco-Roman Wrestler 887-2 record, more such great feats in wrestling in early 20th century like that of Great Gama,
Jahangir Khan (GOAT squash player) 500+ matches winning streak,
Indian hockey team 6 straight Olympic golds with ridiculous margins, 18 years without conceding a goal, once conceded a goal against USA in LA Olympics since goalkeeper was signing autograph and that match was a 24-1 victory (WR)
Kasparov world #1 for 20 years in an era which saw several ATGs including other world champs like Karpov, Anand, Kramnik, Topalov (FIDE)
There may be others like Jordan, Gretzky, Sir Redgrave, Ali, Anderson Silva, Floyd Mayweather Jr all greats in their own ways with some hard to break records. Teams like All Blacks, Boston Celtics (Bill Russell era), Chinese TT/badminton etc.
No point comparing different sports, Nadal is a champ just like the others. Privileged to follow his career.