windows – The Ghost of Opera Browser LOL

I have both uninstalled Opera and also taken out the “Startup” entry that updates Opera, figuring this action WOULD stop it from installing again. But the next day, both [a] Opera Browser and [b] updater entry in registry were back? How and why? If it is bundled with something else, how to tell? CCleaner, for example, how to tell if it IS expected to load as part of terms etc, of installing CCleaner?