I’m pretty sure not, because I’ve turned into twit-pals with a reviewer for a local paper. 
@hwinkler4real responds to his fans, and I’ve seen @kirstiealley do it quite a bit as well
I’ve occasionally seen @realronhoward chat with fans and @damonlindelof answer a question now and again
comics I’ve seen quite a bit:
@pattonoswalt
@iamcolinquinn (the most of any celebrity I’ve seen)
@JimNorton
@rickygervais
musicians:
@flea333
@MikePortnoy
@Scott_Ian
and if you’re into hoarders…@cluttercleaner
The writer Jane Espenson tweets a lot. She did live commentary during the Torchwood specials. She’s writing for Once Upon a Time right now. Husbands is a internet show she created. She often responds to fans that ask about current projects. @JaneEspenson
@jonronson, if he counts as a celebrity. And @AltonBrown has retweeted me.
I sent AB a tweet today, hope he responds! 
@GroovyBruce (Bruce Campbell) is very chatty and responsive.
I’ve gotten a reply from Anthony Bourdain
Came here to say this - he must RT & reply to about 20 or so fan questions a day, and usually includes a photo in each one.
Brett Butt from Corner Gas ( @BrentButt ) is pretty good.
John Hodgman ( @hodgman ) even accepts Scrabble challenges from his fans.
Seth Meyers and Brent Butt have both responded rather quickly to tweets I’ve sent to them.
Marc Maron and Patton Oswalt respond to tweets pretty frequently. Never got a response from Marc, but Patton did “fave” one of my replies to him once, which filled me with fleeting pride.