What's the WordPress hook that is the "earliest" in execution?

I've used the WordPress hook, init, to execute custom code early in WordPress, but is there another hook that executes earlier than开发者_C百科 that?

If this page in the docs is accurate, you have 10 choices for hooks that occur before init.

It seems that the earliest-running Action Hook in Wordpress 4.x is muplugins_loaded. That hook is called after all activated Must-Use Plugins have been loaded.

In the event that mupluginst_loaded might not trigger, the registered_taxonomy plugin fires right after that.