I would say Philip Griffiths in Phantom but he's not a lead.
Michael Crawford in The Phantom of the Opera. Colm Wilkinson in Les Misérables. John Owen-Jones in The Phantom of the Opera (has played the role almost 2,000 times).
J. Mark McVey as Jean Valjean in LES MIZ. Over 3000 times
"TO LOVE ANOTHER PERSON IS TO SEE THE FACE OF GOD"- LES MISERABLES---
"THERE'S A SPECIAL KIND OF PEOPLE KNOWN AS SHOW PEOPLE... WE'RE BORN EVERY NIGHT AT HALF HOUR CALL!"--- CURTAINS
Would he count? I know he played multiple roles throughout his time in PHANTOM.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body
Gavin Lee has played Bert in Mary Poppins for almost 9 years now, he was the original in london, i think he also did the UK tour, the opened broadway, then two years latter went on the US tour for a year, then returned to and has remained with the Broadway production ever since.