The first four Emacs editors, which had something like an extension language: Emacs (1976), EINE (1977), SINE and Multics Emacs (1978). EINE and Multics Emacs were written & extended in Lisp. SINE was using a 'lisp-like' language. A bunch of further Emacs-like editors appeared then.

GNU Emacs later (1984) was based on Gosling Emacs (1981), which was written in C and extended with Mocklisp. Mocklisp was a rather uncomplete Lisp, which was replaced with Emacs Lisp by Richard Stallman.