Como dizer "olha só quem resolveu aparecer" em inglês

Opção:

Look who's here!

Bill: Look who's here! My old friend Fred. How goes it, Fred? Fred: Hi, there, Bill! What's new? Bill: Nothing much. - Thefreedictionary

Outra opção é:

Look who finally showed up!

www.thefreedictionary.com

Look (at) what the cat dragged in!
Inf. Look who's here! (A good-humored and familiar way of showing surprise at someone's presence in a place, especially if the person looks a little rumpled. Compare this with look like something the cat dragged in.) Bob and Mary were standing near the doorway talking when Tom came in. "Look what the cat dragged in!" announced Bob. Mary: Hello, everybody. I'm here! Jane: Look at what the cat dragged in!

Mais uma:

Look who decided to show up!

Hello!

I think we can also use this post for "dar o ar da graça". And there's another post here:

como-dizer-dar-o-ar-de-sua-graca-em-ingles-t31622.html

That's it!

"Look who just breezed in!"

Here's another option (just heard this on a TV program):

Look who's turned up!