Fontspec is a package for XeLaTeX. It provides an automatic and unified interface to feature-rich AAT and OpenType fonts through the NFSS in LaTeX running on XeTeX.

XeTeX (the successor to TeX-GX) is a TeX-variant (originally for Mac OS X, but now available in the major distributions for other platforms, too) that accepts unicode input and can access system fonts directly.

The author is Will Robertson. The package is Copyright © 2004-2008 Will Robertson.