Yup i think so, Microplana terrestris (given by someone else here) seems to match!
Almost definitely a leech. They do live in western Europe, although I've only met them in very watery areas (Friesland)
I was almost sure too but i poured hot water on it to kill it (and kill any from my pipes), and the belly part is white (see pic) and i cant find any leech type with white "belly".
Not an entomologist, but I'm thinking terrestrial flatworm - with the white belly perhaps microplana terrestris?
Looks more like a slug to me
Leeches have distinctive mouths, so there's one way to find out. Well, two ways, I guess. You can put it on your leg and see if it starts sucking your blood. I'd advise just checking its mouth parts.
Reminds me of that X-Files episode with the worm guy
Not a leech, leeches have transversal rings and this guy looks very smooth.
Maybe some kind of flatworm? https://en.m.wikipedia.org/wiki/Platydemus_manokwari
Yup i think so, Microplana terrestris (given by someone else here) seems to match!