Actor with smaller role but regular appearances in film — contributes to plot without being protagonist. Often day-rate deal, not backend participation.
You need someone for your film who regularly appears but doesn't carry the main burden — that's your supporting cast. Unlike extras, who fill a scene and disappear, a supporting actor works with you across multiple sequences. They have character continuity, a function in the story, sometimes even a name. The best friend, the annoying colleague, the background investigator — these roles define the ensemble and give weight to the main story through context.
In practice, supporting actors differ significantly from lead roles in their contractual situation. They are usually calculated on daily rates, not profit participation. This means clarity during casting about shooting schedules and fee structures is essential. I've often experienced a supposedly small role suddenly being expanded — then you're on set with someone whose contract doesn't cover that. Better: go through the actual screen time with the production management and your casting team from the start. Supporting actors are also the testing ground for less known but talented actors. Here they can show they can carry a scene without having full responsibility for the film. Some of my best set experiences arose because a supporting actor brought unexpected depth to a character.
During shooting itself, you need a different preparation than for lead roles. Supporting actors often don't attend every rehearsal, not long preparations. They have to function immediately. Therefore: precise instructions, clear scene objectives, don't dig too deep into psychological holes — unless there's time. You communicate faster, more directly. This saves frustration. A supporting actor who knows they'll be gone in three days values efficiency more than ambitious method acting processes.
Even in editing, the logic changes: supporting actor scenes are often easier to shorten or extend without breaking the overall structure. This makes them valuable for the rough cut — if a sequence runs too long, you first trim around these roles. This is not a disadvantage, but part of their function in the narrative framework. They are the flesh around the bones of the main plot.