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 just outside the Top 80--almost the highest its ever been ranked. It is popular in several counries, 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. Note that though that the initial 'x' does have a distinct appeal, the correct pronunciation has it beginning with a 'z' sound.
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 creatif spelling Xzavier.