BABY NAMES
Jack
American
 Up in popularity
 Down in popularity
 Best bet
 Unisex
Jack is an all-American hero, whether as a president (Jack Kennedy), a man of action (Jack Bauer of 24), or the protagonist of dozens of fairy tales (the guy with the beanstalk; the kid who climbed up a hill with a pail of water).

Variations
Jackey, Jax, Jacqin, Jackie, Jocko, Jaq, Jock, Jackee, Jak, Jacko, Jacques
Popularity rankings from the Social Security Administration
Jack
About name popularity rankings
You may find some surprises -- for example, who knew Jennifer was a boy's name? Because this feature uses actual Social Security data, it includes the human error that attends a large survey, but it still reliably reflects the patterns of naming fashion.