Logan is a a bright and cheerful Scottish surname that originated from a place of that name in Ayrshire. Logan has been climbing steadily since the mid-70s; it was in the Top 20 from 2006 to 2011, fell slightly, and is now back at Number 18. Not surprisingly, Logan is mega-popular in its native Scotland--now Number 7--AND also in Wales.
The mutant character Wolverine, known as Logan, based on the X-Men comics and played by Hugh Jackman on film, has had a considerable impact on the name. There were also attractive guys named Logan on Veronica Mars and Gilmore Girls.
Logan is also used for girls, but less so now than it was in the mid-nineties.