As in,
William Butler.
That's what I'd think of anyway.
Besides thinking it's surnamey-trendy. So many surname-trend names seem lame to me - ones with -ton, -son, -er, and ending in -s particularly - like they're trying to make the person seem like someone s/he's not, or trying to create an aura of "uppaclass" or "romantic oldtime manners" or "one of the good ol' boys" or somesuch. I can appreciate names with romantic, heroic, or theatrical associations, but surnames seem to do it so artificially.
Anyway, Yeats, a poet-name, okay - I think it's lame, but it's not unacceptable.