No, but she’s from the same show.
Clue 1: I’m a dancer recently turned actress.
Clue 2: When I was a kid, I appeared in The Philosopher’s Stone. I’m one of the few Americans to be in a Harry Potter film.
Clue 3: My brother is also a dancer and, like me, went into the spotlight in a popular dancing reality show.
Clue 4: I’m a two-time winner of said reality show. It’s a reality show exclusively about DANCING.
Clue 5: I’m blonde.
Kym Johnson?
No 
This is getting mad!
Clue 1: I’m a dancer recently turned actress.
Clue 2: When I was a kid, I appeared in The Philosopher’s Stone. I’m one of the few Americans to be in a Harry Potter film.
Clue 3: My brother is also a dancer and, like me, went into the spotlight in a popular dancing reality show.
Clue 4: I’m a two-time winner of said reality show. It’s a reality show exclusively about DANCING.
Clue 5: I’m blonde.
Clue 6: I was in a recent movie with fellow blondies Christina Aguilera and Kristen Bell.
Julianne Hough? It says she played in hp1 and is in Burlesque 
Finally!
Yes, it’s Julianne. I’ve never watched her reality, as I met her after that, but I’m friends with her, and I’ve been wanting to put her in here for a while. She’s really sweet!
Here are the clues:
Clue 1: I’m a dancer recently turned actress.
She got her big break dancing, but now she’s been acting for a couple of years.
Clue 2: When I was a kid, I appeared in The Philosopher’s Stone. I’m one of the few Americans to be in a Harry Potter film.
When she was little, she was an extra Gryffindor student. She’s particularly visible during the Quidditch match.
Clue 3: My brother is also a dancer and, like me, went into the spotlight in a popular dancing reality show.
She has a dancer brother and both participated in Dancing with the Stars.
Clue 4: I’m a two-time winner of said reality show. It’s a reality show exclusively about DANCING.
She won in the 4th and 5th season.
Clue 5: I’m blonde.
She is. And very good looking too.
Clue 6: I was in a recent movie with fellow blondies Christina Aguilera and Kristen Bell.
That was Burlesque.
Finally!!! Ok:
I am a singer who acts and was born in Tennessee! Also, I have a movie coming out soon.
Miley Cyrus?
No. I am a male actor and have appeared on SNL.
Justin Timberlake.
Yeah. I knew mentioning SNL would give it away
Not really. I don’t watch SNL. But I searched for singers who became actors. I don’t know many, but then I remembered Timberlake is from Tennessee.
Clue 1: I’m a famous English actor who suffers from a hand condition called Dupuytren’s contracture.
Bill Nighy?
Yeah!
Your move.
I am a comedian and educator and I got my name on a comedy show. I also developed a part still used in the Boeing 747. I am NOT from Tennessee
Bill Nye
Correct. Your turn, sir
Easy one cause I’ve gotta go.
Clue 1: I’m a famous Hawaiian actress who was raised in Australia.
Nicole Kidman?
Yeah, not my best effort
I’m a male actor, and my good-looking wife is much younger than me.