Modern directors with the best track record of “discovering” talent

I was thinking about some of our still-working theatre directors and despite a very uneven output, Michael Mayer has a damn good track record of identifying emerging artists or people whose talents haven’t been properly used yet:

• CHARLIE BROWN — Kristin Chenoweth and Roger Bart
• MILLIE — Sutton Foster, Gavin Creel, and to a lesser extent Marc Kudisch
• SPRING AWAKENING — Jonathan Groff, Lea Michele (plus her comeback), John Gallagher, and that whole supporting cast & replacement cast who’ve gone on to great things.
• ON A CLEAR DAY — Jessie Mueller
• HEDWIG — Lena Hall
• SIDE MAN — Frank Wood

Nicholas Hytner is another:

• MISS SAIGON — Lea Salonga (and something of a step up for Jonathan Pryce)
• CAROUSEL — Audra McDonald
• SWEET SMELL OF SUCCESS was an important stepping-stone for people like Kelli O’Hara and Brian D’Arcy James
• THE HISTORY BOYS — James Corden, Russell Tovey, Jamie Parker, Dominic Cooper, Sam Barnett

Tommy Kail is obviously one, considering where those original casts of HEIGHTS and HAMILTON have gone.

Honorable mentions to Michael Greif (Rent, DEH, Hell's Kitchen) and Jerry Zaks in the 80s/90s (Nathan Lane, Courtney B. Vance, Faith Prince, Ben Stiller).

Who are some others who are still alive & working?

[I am aware that many of the above actors worked prior to these credits. These directors brought out the performances that took their careers to the next level.]

SeanD2 said: "I think Jeremy Sams has to be under consideration if only for the cast of 13 including Ariana, Liz, and Allie. But he also did Noises Off which was huge for TR Knight andAmour which was Christopher Fitzgerald's Broadway debut,"

The 2001 Broadway revival of NOISES OFF definitely changed T.R. Knight’s life as he got cast as a regular on GREY’S ANATOMY from this. I remember him exiting the Brooks Atkinson stage door wearing his Bed, Bath and Beyond work shirt and name tag as he was still working part-time there between his performances on Broadway. The reality versus the fantasy of working on Broadway.

There's a pretty strong argument to be made that Idina Menzel is going to be looked at as one of the most important performers in the history of musical theatre, as a pivotal figure in the ending of the 1960s's "great divorce" between musicals and mainstream pop culture. Lin-Manuel Miranda may have finally torn the lid off, but Idina's work popped a LOT of the nails out.

In other words, Michael Greif making a star of her in Rent may be a bigger butterfly-effect moment for musical theatre than we have entirely reckoned with yet.

I can almost see someone reading Sweet Smell of Success and thinking Days of Wine and Roses lol.

After I read the thread title but before I opened it, Michael Mayer was the first person I thought of, due to the names you listed plus Stark Sands (and Joshua Henry, in ensemble and then a replacement in a role) in American Idiot.