Please answer a question about the following article about Late Middle Ages:

At the end of the Late Middle Ages, professional actors began to appear in England and Europe. Richard III and Henry VII both maintained small companies of professional actors. Their plays were performed in the Great Hall of a nobleman's residence, often with a raised platform at one end for the audience and a "screen" at the other for the actors. Also important were Mummers' plays, performed during the Christmas season, and court masques. These masques were especially popular during the reign of Henry VIII who had a House of Revels built and an Office of Revels established in 1545.

Who performed the seasonal Christmas plays?
Mummers