NetBSD is a free, secure, and highly portable UNIX-like operating system available for many platforms, from 64-bit AlphaServers and desktop systems to handheld and embedded devices. Its clean design and advanced features make it excellent in both production and research environments, and it is user-supported with complete source. Many applications are easily available.

Currently you have a choice CLISP, ECL and SBCL as packaged for NetBSD.

UtiLisp32 is also available in the NetBSD package collection

Other Common Lisp implementations work on NetBSD as well, even if they aren't packaged separately for it: see CMUCL.