When I read that The Old Dark House was something of a comedy, I thought: oh, no, another movie mangled by slapstick English goofiness. I was surprised to discover that it was extremely creepy, atmospheric, and filled with bizarre characters.

Each member of the Femm family, along with their servants, are secretive, menacing, even dangerous, not merely odd. In short, they’re weird. Karloff’s Morgan and Elspeth Dudgeon’s Roderick are as frightening as any ghost or monster. Eva Moore’s Rebecca not only acts strange, with her distorted reflections in the mirror, she’s hideous.
The storm-stranded guests who, as incredulous witnesses, seem to be the victims of a collective nightmare. Charles Laughton as a blow-hard aristocrat, typifies the innocent eccentricity of the guests juxtaposed to the macabre house and family.

Some folks feel let down by the ending; but I think it adds to the nightmare aspect of the film. Daytime means a return to the normal world, as though the events of the previous night never happened. The heightened strangeness of the setting shows a dream-like tint, where things seem a little off, and people are somehow unnatural.
At the same time, the fact that there’s nothing supernatural going on makes it scarier. Reality seems supernatural in The Old Dark House. 9/10.