* [[Wikipedia:Richard Stallman|Richard M. Stallman]] features as the replacement for the [[Romero's head|boss brain]] ([https://github.com/freedoom/freedoom/tree/master/sprites/jonr sprites]).
* The texture SP_FACE1 is derived from pictures of prominent members of the Doom community ([https://github.com/freedoom/freedoom/blob/master/patches/linguica/wall25_1.gif texture]).
* In versions up to 0.5, the [[pink fish]] popular in some Doom community forums is used instead of [[Commander Keen]]. The sprite was removed after 0.5 due to trademark concerns.
==Commercial derivatives==