The Gforth project was started in mid-1992 by Bernd Paysan and Anton Ertl. The third major author was Jens Wilke. Neal Crook contributed a lot to the manual. Assemblers and disassemblers were contributed by Andrew McKewan, Christian Pirker, Bernd Thallner, and Michal Revucky. Lennart Benschop (who was one of Gforth’s first users, in mid-1993) and Stuart Ramsden inspired us with their continuous feedback. Lennart Benshop contributed glosgen.fs, while Stuart Ramsden has been working on automatic support for calling C libraries. Helpful comments also came from Paul Kleinrubatscher, Christian Pirker, Dirk Zoller, Marcel Hendrix, John Wavrik, Barrie Stott, Marc de Groot, Jorge Acerada, Bruce Hoyt, Robert Epprecht, Dennis Ruffer and David N. Williams. Since the release of Gforth-0.2.1 there were also helpful comments from many others; thank you all, sorry for not listing you here (but digging through my mailbox to extract your names is on my to-do list).
Gforth also owes a lot to the authors of the tools we used (GCC, CVS, and autoconf, among others), and to the creators of the Internet: Gforth was developed across the Internet, and its authors did not meet physically for the first 4 years of development.
Gforth descends from bigFORTH (1993) and fig-Forth. Of course, a significant part of the design of Gforth was prescribed by Standard Forth.
Bernd Paysan wrote bigFORTH, a descendent from TurboForth, an unreleased 32 bit native code version of VolksForth for the Atari ST, written mostly by Dietrich Weineck.
VolksForth was written by Klaus Schleisiek, Bernd Pennemann, Georg Rehfeld and Dietrich Weineck for the C64 (called UltraForth there) in the mid-80s and ported to the Atari ST in 1986. It descends from fig-Forth.
A team led by Bill Ragsdale implemented fig-Forth on many processors in 1979. Robert Selzer and Bill Ragsdale developed the original implementation of fig-Forth for the 6502 based on microForth.
The principal architect of microForth was Dean Sanderson. microForth was FORTH, Inc.’s first off-the-shelf product. It was developed in 1976 for the 1802, and subsequently implemented on the 8080, the 6800 and the Z80.
All earlier Forth systems were custom-made, usually by Charles Moore, who discovered (as he puts it) Forth during the late 60s. The first full Forth existed in 1971.
A part of the information in this section comes from The Evolution of Forth by Elizabeth D. Rather, Donald R. Colburn and Charles H. Moore, presented at the HOPL-II conference and preprinted in SIGPLAN Notices 28(3), 1993. You can find more historical and genealogical information about Forth there. For a more general (and graphical) Forth family tree look see https://www.complang.tuwien.ac.at/forth/family-tree/, Forth Family Tree and Timeline.