Erich Boleyn originally designed and implemented GRUB.

VaX#n8 (real name unknown) wrote shared_src/fsys_ext2fs.c.

Heiko Schroeder rewrote shared_src/stage1.S to be more readable.

The following authors assigned copyright on their work to the Free
Software Foundation:

Gordon Matzigkeit adopted GRUB into the GNU Project.  He fixed several
bugs, added symbolic link support to shared_src/fsys_ext2fs.c, and
began the implementation of /sbin/grub.

OKUJI Yoshinori contributed many bugfixes and new features, such as
working LBA support, /sbin/grub support for configuration files, the
script /sbin/grub-install, the utility /bin/mbchk, the new engine for
builtin commands, disk swapping support, keyboard configuration support,
network support, online help support, command-line history support,
hidden menu support, the new Linux loader, serial terminal support,
single-line editing support, and several new commands.

Peter Astrand added support for a color menu.

Pavel Roskin contributed many bugfixes and new features, such as FreeBSD
support for the grub shell, and configure process cleanups.

Klaus Reichl wrote stage2/fsys_minix.c.

Per Lundberg added graphics support to the Multiboot Specification.

Jochen Hoenicke rewrote stage2/fsys_fat.c and wrote
stage2/fsys_reiserfs.c and stage2/md5.c.

Christoph Plattner added support for Net Boot Image Proposal.

Stefan Ondrejicka added the commands "partnew" and "parttype".