In the movie Hateful Eight by Quentin Tarantino there is a recurring theme played by a low-sounding brass instrument. You can hear it in this piece.
Is this a kind of tuba or horn?
I'm tempted to say contrabassoon, as the instrument playing the seriously low D starting in the 2nd bar. For the rest of that phrase, I'd be hard-pressed to distinguish whether it was bassoon or contra-
The later section starting 0.46, I'd definitely go for contra- with what may be tuba above it.
I found this quote from Morricone, reported by the BBC
The main instruments introducing this piece are the bassoon, the contra-bassoon and the tuba,