* Symbian
* Palm webOS
* Mozilla (I think that was also called WebOS?)
* Jola
* Some blackberry thing based on QNX that "supported" Android apps
* Tizan
* Windows Phone
* Ubuntu Phone
Plus a bunch of independent / hobby(?) ones that never really took off, eg the Inferno portThese days it feels like most people have given up trying to compete against Apple and Google.