There have been various actor related developments in Smalltalk and others on YC will have far more knowledge :-) But Distributed Smalltalk (John Bennet et al)

There have been various actor related developments in Smalltalk and others on YC will have far more knowledge :-) But Distributed Smalltalk (John Bennet et al) - late 1980's dabbled with actor like constructs. JOhn's thesis is still worth a read. Actalk originally by Jean-Pierre Briot has been around since 1989 (and has supported implementations for Squeak and Pharo thanks to Serge Stinckwich). TOny Garnock Jones - Squeak Actors (https://tonyg.github.io/squeak-actors/ https://tonyg.github.io/squeak-actors/) is (I think) the most recent implementation (and is lots of fun to use).