There’s definitely a Scottish theme appearing here.
All mostly female in the UK, too, nowadays.
Funny, Connor is another one I was going to mention I hear a lot among the small set (5 & under).
And I would add Lindsay (which I think someone else mentioned), and Ashley.
I read once that it is common for male names to “become” female names, but that they never move in the other direction…once it’s a female name, it stays a female name.
One of my good friends named her son Aidan.
I thought the weird ones from the list were: Callum, Archie, Kieran, Finlay/Finley, Rhys, Kian, Kai and Luca.
Ah, well, I’m not around kids much, so that would explain it. That doesn’t explain how I know there’s a fad for Celtic names in the U.S. right now, though. 
Chalk it up to cultural osmosis, I guess.
Neither Wat nor Hamish are known in the US.
Ivor doesn’t appear on GorillaMan’s list, but I’m sure you’re much more likely to hear it in the UK than in the States.
I have a brother named Erin and know of several female Erin’s, but have never met or heard of another guy with that spelling of it.
I wish my husband would get some of that osmosis! 
We are trying to come up with boy’s names, so I am very tuned into what is trendy right now. He likes the Celtic sounding names (at least we are both part Irish!), but I just don’t want junior to be Connor #4 in his classroom, you know?
OAP = Old Age Pensioner
One of my brothers is named Conor, with just the one “n” and he’s 26 years old. Still don’t see too many Brendans (one of my other brothers).
What about Ruprecht?
And we don’t name our children Niles or Jeeves fearing they will move to the UK and become butlers. 
I pronounce it “ee-an.” According to my husband (Ian), he knows of several blokes back over there called “eye-an.” And then you factor in the other spelling, Iain… just adds to the confusion I guess.
I knew about the Ian on 90210 and thought it was weird that he pronounced his name the other way. I’d say that about half of the people we encounter here know about that famous Ian & assume my husband’s name is “eye-an.” The other half, well, they’re just not familiar with the name period. We (Kansas Citians) aren’t exposed to many different cultures or accents that a native of a larger, or coastal city might be. <— Blanket statement, I know. But really, I have a hunch that most Brits who move over here for employment opportunities would have better luck in a larger city than this cow town.
I hope you don’t misunderstand me…I don’t dislike the name at all! I think it’s nice…I’m just trying to avoid the trendiness, at least a little.
Funny story…one of the Connors I know has a brother named Brendan!
Very few Welsh names are common in the U.S., but then, they’re not common in England either. (And when they are used, they’re mispronounded. Rhys is more like Hreese, and Ieuan is yey-ann.) A few of the ones I’ve encountered in under-30s:
F: Angharad, Bethan, Gwenno, Hawys, Mabli, Nia, Rhiannon
M: Geraint, Iestyn, Illtud, Llyr, Owain (o-wine)
The pronunciation of this one depends on which Welsh accent is being employed (o-when and or-when are other versions I’ve heard from Welsh mouths)
Written by an under-30 English-born Owain who says ‘Owen’, and couldn’t give a toss how it gets said or whether it gets spelt Eoin or Eoghan, either…
Another old-man name.
And whoever mentioned Lindsay (& Lindsey), any young people with these names are female.
No misunderstanding at all. I was trying to illustrate that it’s not just a trendy thing, unless my mom is way more hip than she’s ever let on. She was stuck coming up with Irish names that couldn’t be shortened to a nickname as easily. My dad was “Billy” his whole life and hated it. So we got Ryan, Conor, Brendan, and Kevin.
Kevin? Not easily shortened? I guess after the fourth birth, she was a bit tired 
Well, of course, they are real names, given to real Irish people for a long time…didn’t mean to imply that they aren’t!
My almost-3-year-old son’s name is Connor. And I can attest, he will not have a hard time finding souvenirs with his name on them in a few years. There are now a lot of little boys with that name (or with the more proper Irish spelling, Conor).