My friend Jill suggested the Redgrave sisters:

Diva: Vanessa Redgrave

Mensch: Lynn Redgrave

Naturally Vanessa is the diva, she's so much more grand and frosty. But it gets a bit more complicated when you think of their TV movie version of *What Ever Happened To Baby Jane?* in which Lynn played the diva role of Jane and Vanessa played the mensch role of Blanche. Here's a clip: