I've made it known I'm unimpressed with published overviews of Baptist theologians. The ones that are out there are too denominationally focused, often don't include women (surely there must be some) or non-British/American thinkers. Together lets list the thinkers that would make for a good volume from a variety of traditions, geographic locations, historical periods and genders.
Here's a few quickly off the top of my head I think would be essential to such a volume:
John Smyth
Thomas Helwys
Thomas Grantham
John Bunyan
Oswald Chambers
C.H. Spurgeon
E.Y. Mullins
Johann Gerhard Oncken
Walter Rauschenbusch
Martin Luther King, Jr.
Clark Pinnock
John Piper
Carl F.H. Henry
I know I'm forgetting several so who are the big dogs from your tradition? Who are some women baptist theologians of some prominence? Who might be some contemporary or historical names from Asia, Africa, Europe, Eastern Europe, South America, Central America, Australia?