Namesakes
Characters in Celtic Mythology:
1 character
Cai (a.k.a. Kai) (m) 
Nobel Prize Winners:
1 physics
(physics) Kai Siegbahn 1981
Notable Actors and Entertainers:
1 actor
Xosha Roquemore (middle name Kai) 1984-
Notable Athletes:
1 skating
(skating) Kai Verbij 1994-
Notable Scientists and Inventors:
1 physicist
Kai Siegbahn 1918-2007
Olympic Medalists:
1 bronze/silver/gold, 1 gold/bronze, 1 silver
(silver) Kai Suikkanen 1988 ice hockey
(gold/bronze) Zou Kai 2008; 2012 artistic gymnastics
(bronze/silver/gold) Qin Kai 2008; 2012 diving - springboard; diving - synchronized springboard