You missed a pretty big one, Dr. H. H. Holmes. He designed and built a hotel specifically to enable him to kill people, with poorly-lit hallways, doors that could be sealed by him, a special soundproof, airtight vault, his own crematorium room, and a basement medical room. Nine confirmed kills, twenty-seven confessed kills, 200+ suspected murders. Hid some of the bodies by having a guy come in, strip the bodies, and sell the skeletons to medical schools.
The hotel was part of his little business park there. He seduced the wife of a guy working for him once, convinced her and her daughter to stay with him when the husband left, then killed them either on Christmas Eve or Christmas Day. Even had a few minions working for him who helped him find beautiful women.
I recommend the book The Devil in the White City if you like that and a little bit of history about the 1893 World's Fair(which gave us, among other things, the Ferris Wheel and Pabst Blue Ribbon).