Back to the seinen anime, Monster fits into the category of mystery/thriller. For science fiction/horror see Parasyte -the maxim- and for dark fantasy see Berserk.
Be sure to not watch the 2016 anime series, as it is reviled for its poor animation. The 1997 anime series or the film trilogy from 2012 are a better use of your time. Both cover the same section of the story. However, be forewarned the part they adapt is a specific arc of the story near the beginning and is thus unfinished. Still worth it.
But I’d still recommend you start with Monster if you’re looking for something closer to live-action shows.
