Though there have been exceptions to this, almost all senior royals (including Prince Charles, Prince William, Prince Harry, and all three of the Cambridge children) are christened by the Archbishop of Canterbury. As Meghan Markle herself was christened and confirmed by the current Archbishop of Canterbury, Justin Welby, before marrying Prince Harry, it's likely that he will baptize baby Archie as well. Notably, Queen Elizabeth was actually christened by the Archbishop of York in 1926.