XLisp
XLisp is the name for several historic Lisp dialects developed by David Betz that was popular for small microcomputers in the 1980s and 1990s. XLisp is fairly portable and has versions running on a variety of Unix systems, MS Windows, and older versions for DOS.

http://www.xlisp.org/

XLISP-PLUS has recent binaries for Mac OS X and Linux

Older XLisp releases on the CMU AI repository are suitable for retrocomputing.