Eleanor Roosevelt - couldn't even begin to suggest who to base her on. :/
Ishtari? (Babylonia) - Can't even figure out who this is supposed to be, unless it's some weird take on the goddess Ishtar. Definitely want some kind of Babylonian female, but up for suggestions on who it should be.
Cunobelinus (Celtia/Wales?) - Based on the one in the upper-left, maybe Suryavarman?
Hippolyta? (Greece) - Erm, Hippolyta was an Amazon, who according to Herodotus were even less Greek than the Macedonians.

Still, seems like I oughta use her
somewhere...Based on this pic, actually looks awfully close to
Ekmek's Theodora, whoever she's based on...
Indira Gandhi, as previously mentioned.
Amaterasu (Japan) - Uhm...well, maybe not so much. But definitely some Japanese female or other, and if she's based on this pic...uh, maybe Hatshepsut?
Börte (Mongol) - Hmm...actually, Ekaterina looked a lot like this when she got older, so maybe use her?
Sacagawea (NatAmer/Sioux) - Ooh, man, this one could take some work; I can't see anyone with that round a face, especially with the high indian cheekbones...
Osman I (Ottomans) - Actually, I think Qin Shi Huang would be a great base for him, with those big freakin' huge jowls.
Livia (Rome) - Isabella, maybe?
Gunnhild, Mother of Kings (Viking) - I think I'ma go with Liz on this one.
Shakala? (Zulu) - I'm almost certain this one's fictitious, not even based on a mythological figure, just a permutation of "Shaka". Anyone for freestylin'?