Donald Knuth conceived and implemented TeX, Metafont, and WEB.
John Hobby wrote MetaPost (partially derived from Metafont) and dvitomp.
Peter Breitenlohner wrote dvicopy.
Tomas Rokicki wrote gftopk, pktogf, and pktype.
Frank Liang wrote patgen version 1, and Peter Breitenlohner did patgen 2.
Oren Patashnik wrote BibTeX.
Michael Ferguson and Bernd Raichle wrote the MLTeX extensions.
Ignacio Zabala implemented DOC, the prototype for WEB.

Howard Trickey and Pavel Curtis initially ported TeX and related
  programs to Unix.
Paul Richards initially ported Metafont.
Pierre MacKay initially ported the MFware programs.
Richard Furuta initially ported some of the TeXware programs.
Ulrik Vieth initially adapted MetaPost to Kpathsea.

Tomas Rokicki wrote the original TeX to C program.
Tim Morgan made most of the subsequent changes.

Dozens of other people have contributed to porting, bug fixes, and other
improvements.  (The names are recorded in the ChangeLogs to the best of
my knowledgement. Do not hesitate to contact me with corrections.)

K. Berry <kb@mail.tug.org> is the current maintainer.