Proprietor is a type of NPC that is featured in the The Sims 3: Showtime. In Late Night, an agent can call a Sim who has created a band and request that the band play a gig in their bar or club; this is similar to a proprietor.
If they're present in a lot, it contains a bar, the proprietor will serve juice at random, and a Sim can request to buy a round of drinks, a drink for themselves or even for another Sim. Random townies are the only Sims that can work as proprietors. The player can also have their Sim ask a proprietor to land them the acrobat, magician or singer profession. Proprietors are also needed on the lot to introduce performers at SimFests.
On a select few prebuilt lots, there is an object known as a proprietor placement, usually placed near some kind of desk. It has not been studied well how it works like.