[arch-general] Pacman: Remove unneded dependencies

Hi, I know, this is probably a very common question, but I couldn't find any information on the pacman wiki article about that, so I have to ask. How can I uninstall all packages on my system, which have been installed as a dependency, and aren't needed any longer? (Because I've uninstalled the dependent package or because the dependent package no longer depends on that dependency) I've read about pacman -Qe, but this lists packages I've explicitly installed and don't want to remove. And please, don't just point to the wiki article, I've checked that already. Thanks in advance, Lukas