Are there any object-oriented programming languages that are not based on the class paradigm?
As far as I know, Self is the original language that invented the "class-free" paradigm based on prototypes. It already existed (in an experimental stage) in the 1980s and pushes Smalltalk's elegant usage of the prototype pattern to the extreme, such that classes are completely eliminated. 

It influenced all the other "class-free" OO languages I know of: 


most prominently Javascript, 
the classical programming language and environment Squeak (which is built on top of Smalltalk) 
the multi-paradigm script language Lua.

