The building manager is responsible for the building's maintenance and collecting the [1] from its tenants. He or she has only been mentioned in the series.
In "The Financial Permeability" (S02E14), Penny tells Sheldon that she saw the building manager showing an apartment downstairs and she has not paid her rent, so she has to hide from the manager.
When Sheldon is locked out of his apartment, Penny calls the building manager to open the door, but the manager does not show up that evening, in "The Vegas Renormalization" (S02E21).
Penny hiding from the building manager.