Jarethan said: "Clearly not an exhaustive list, but they would include:
Joel Gray won a supporting Tony for Cabaret. That it was ever a supporting role is, of course, debatable.
Is Big Daddy a supporting role?If so, most definitely add him.
Is Scout in TKAM really a supporting role? If so, most definitely add her.
Is Che in Evita really...If so, add him.
Bananas in The House of Blue Leaves.
Absolutely agree re Lafayette / Jefferson. I still don't know how Deveed Diggs got all the words out. The others I have seen did, but their words were not as succinctas his.
Moritz in Spring Awakening.
To do it well night after night, the role of Genie must qualify.
The role of the wife (can't remember her name) in King Hedley 2.
Birdie in The Little Foxes.
The Black wife in Slave Play.
Smikein Nicholas Nickelby.
James Thunder Early in Dreamgirls.
Honey in Virginia Woolf.
Josie's father in Moon for the Misbegotten.
James Tyrone Jr. in LDJIN.
Laura in The Glass Menagerie.
Sister Agnes in Agnes of God.
Valentin in Kiss of the Spider Woman.
Horst in Bent.
"
Some of these that you mentioned will be contentious, I’d say are leads, such as the Emcee and Che, which are indeed very hard, even ranking up fairly high on leading roles.
Also, for the poster who mentioned Persephone in response to my original post, I agree. I actually considered putting her there, but I changed it at the last second. She’s definitely on a similar level or acting difficulty with Hades, as those two are by far the most developed roles in the show. I didn’t put her in initially because while difficult, her vocals are nowhere near as hard as Hades’. But the more I think of it, her singing is so different from other roles, and she also has to do some truly unique dancing, so she’s definitely high up on the more difficult supporting roles, although I still think Hades is the most difficult role in the show. Funnily enough, I’d say Eurydice is by far the easiest role in the show despite being a lead. Compared to the other parts, her music is a lot more straightforward.