Never heard of Kerry Ellis? That's probably because you're an American who has never been to London and seen a West End play.
Ms. Ellis is as big a star there as Patti LuPone and Betty Buckley have been on Broadway.
Her credits include the Queen musical We Will Rock You at the Dominion Theatre, the role of Fantine in Les Misérables, and the role of Nancy in a 2010 production of Oliver! Oh yes, and she also played the role of Elphaba in Wicked at London's Apollo Victoria Theatre from 2006 to 2009, and also reprised the role at the Gershwin Theatre in New York in 2014 - her only American credit of note, at least so far.
When she's not appearing on the West End, Ms. Ellis is doing TV appearances in Britain and Ireland, appearing in British touring companies, and also making records of various show tunes. She's regarded as the leading lady of British musical theater, and and hopefully she'll perform stateside again.