If the main attendant to the bridesmaid is unmarried, she is known as the "maid of honour." If the main attendant is married, however, she is referred to as the "matron of honour."
unmarried bridesmaid married bridesmatron
She would still be referred to as a bridesmaid, regardless of her marital status.
An attendant in a royal palace is called an attendant or a servant.
She would traditionally be called the Maid of Honor (unmarried) or Matron of Honor (married or divorced).
The commonly-used masculine noun equivalent to bridesmaid(s) is groomsman or groomsmen. You could also refer to them as bride's (or groom's) attendants.A non-gender-specific term is wedding attendant.
equerry
attendant.
A junior bridesmaid is someone that is a minor, but they are still acting bridesmaid.
A kennel attendant.
A washroom attendant.
its called a Lady-in-waiting
Laundry Attendant