Does Avenue Q count as a long running show? For me, it would have to be John Owen-Jones in Phantom of the Opera. Longest running Phantom in the West End; personally, I think he is the ideal Phantom. I love his voice and everything he does on stage =)
"I haven't got a pail."
"Find your grail, your GRAIL!"
"But it's not missing. It's right on the counter where it's supposed to- defying gravity, my giant cup's gone!"
"Five hundred, twenty-five thousand, six hundred minutes. How do you measure... measure a year?"
"How many times do I have to tell you, it's five hundred twenty-five thousand, five hundred and eighty-five point thirty-two minutes. You will never graduate if you keep basing your math on showtunes."
"You ruin Broadway for me."
"As well I should."