Such a person is a porter.
A knight
The flagbearer.
Surrogate.
A medical term based on the name of a person is an eponym.
The person is called a Porter.
tax attorney
That person is the 'barbecuer'.
It get its name from its father who created it or some fantasy tht person carries within him
Food vendor
Dermatologist.
Urethra, or if you mean something that aids in getting urine out of the body, it would be a catheter.