Raised by Wolves
Beforeigners and The Lazarus Experiment (after HBO Nordic went to Sky Atlantic, I assumed that they weren't continuing with Beforeigners because they had TLE, but then the cancelled that too)
Alphas. Seriously what the fuck kind of person doesn't renew it for a 3 episode special to close that cliff hanger.
Recently? Papergirls. I haven't seen it, but I saw the trailer and was going to watch it with my daughter but then the cancellation announcement came so we didn't bother.
I didn't watch it when it first came out as I had absolutely no idea it existed.