Xavier is one of the only X names most people know and use, often as a middle name following Francis, as in Saint Francis Xavier, cofounder of the Jesuit order, who got his name from the Spanish-Basque village where he was born.
Today's parents are beginning to reassess Xavier, now at Number 90--almost the highest it has ever been ranked. It is popular in several countries, and is in the Top 15 in Quebec.
Xavier was chosen for their sons by Donnie Wahlberg and Tilda Swinton-- as well as for the middle name of Larenz Tate's son Miles and Kim Fields' Quincy. Many Americans pronounce the iniitial X, as in ex-ZAY-vee-er, but it's equally accepted to pronounce the name ZAY-vee-er, closer to the French pronunciation.
The Spanish classic Javier, pronounced HAH-vee-ay, has come into greater prominence via Oscar-winning Javier Bardem.
Trivia note: the X-men comics introduced the kreeatif spelling Xzavier.