Actors who are/were also writers

You need to define "actor" or this will soon get silly. I reckon half of listed directors will also have acting credits. Most of these will be small parts and quite a lot are just vanity cameos. If you do not eliminate these, the list will run to literally thousands. With small indie companies and many third world companies, it is almost the norm for the directors to take a part, either to set an example or to save money or to advertise themselves.

I know had I ever directed a movie, I would have wanted my mum to see me.