There are many custom actors written for Isadora if you search the forum.
They are pretty handy and increasingly becoming more popular (you clever people!) I myself can’t code so I do not have any of my own. These are NOT to be confused with user actors. These are actual actors programmed from the ground up using source code and SDK files.
Don’t let this put you off! If you are on Mac then this is how you can install them on your machine….
And for those who wonder how to install the compiled plugin under Windows : just copy the .dll file into ‘IsadoraInstallationFolder\Isadora Plugins’, e.g. C:\Program Files\Isadora\Isadora Plugins. Don’t forget to restart Isadora. The plugin should then show up in the list! (Thanks djinoui)