If you loved The Apartment, try Stalag 17
A bridge between a film you've already seen and one most people haven't. Stalag 17 has roughly 4.0× fewer votes than The Apartment — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Billy Wilder, and they both carry the pitch black mood tag, and they sit in Comedy / Drama territory. If that's the register that drew you to The Apartment, the second film will land in a comparable space — through a different lens.
What Stalag 17 is
A prisoner-of-war sitcom set in a Nazi camp would seem tone-deaf if the jokes weren’t so precise. A barracks hustler makes bank trading with guards until someone starts snitching to them. The only thing sharper than the dialogue is the moral compass that spins wildly off its axis.

