John

From the experts:

John reigned as the most popular of all boys' Christian names for 400 years, from the time the first Crusaders carried it back to Britain until the 1950s, at which point American baby namers finally seemed to be tiring of this most straight-arrow, almost anonymous John Doe of names and started to replace it with fancier forms like Jonathan and the imported Sean and Ian. John was a key name in early Christianity, borne by John the Baptist, John the Apostle and John the Evangelist, plus 84 saints and 23 popes, as well as kings and countless other illustrious notables.

Because many of today's baby Johns get their names for familial rather than stylistic reasons, John isn't as ubiquitous as it once was. For modern parents, the nickname Jack feels much fresher.

The international versions of John are perennial classics in their own cultures: the French Jean, the Irish Sean, the Scottish Ian, the Welsh Evan and Ewan, the Italian Giovanni, the Spanish Juan, the German Johann/Johannes, the Slavic Jan, the Russian Ivan, and on and on.

Celebrities who have gone with the timeless John include Michelle Pfeiffer, Bono, Johnny Depp, Lauryn Hill, Bridget Moynahan and Rob Lowe.