ManKai Common Lisp is a member of the KCL Family through its ECL branch. MKCL is a quite complete ANSI Common Lisp implementation, mainly developed by Jean-Claude Beaudoin at the moment.
MKCL features, in its permanent configuration, a number of significant extensions like multi-threading, FFI and Unicode support, along with a good set of prepackaged libraries: CFFI, Babel, alexandria, FiveAM, Bordeaux-Threads, ASDF, SLIME and more.
The main MKCL project page can be found at http://common-lisp.net/project/mkcl.
Current stable version: 1.1.11 (released on 2019/05/02).