I'm sure his billions of dollars will be able to straighten out the visa application.

The EU — which doesn’t include all European nations — has 24 official languages and 3 official character sets. The Danish name for the EU contains an æ (“Den Europæiske Union”). Prior heads of state of current members include Μακάριος Γ΄, with the gamma translating as “III” (i.e. “the third”). The UK has a very relaxed attitude to name changing, hence the story of Mr. Yellow-Rat Foxysquirrel Fairydiddle.

Unless Musk tries to name future kids in Emoji, European nations can probably already cope with any of this sort of thing.

I think single-letter names were already in thing in the US before that. X Musk is probably fairly recognizable.