During the Elizabethan era, women were not allowed to act on the stage. Men believed it would be indecent for them to participate in theater. As a result, the female roles in plays were played by young boys in white make-up and wigs. Boys and young men tended to lack beards, so they were able to more convincingly portray women and girl characters than mature men who had gone through puberty.
Evidence suggests these boy actors were no older than twenty-one years old. Some would go on to play mature male roles once they were considered too old for the female parts. Several actors in the King's Men, like Richard Sharpe and John Honyman, probably did this. The heyday of boy actors would come end when women were legally allowed on the English stage in the late seventeenth century.
As for boy actors in Shakespeare's plays, Robert Gough was a boy actor who took on many heroine roles during Shakespeare's heyday. He was more than likely the first actor to play Juliet in Romeo and Juliet, a role he performed at age 14 or 15 opposite 28-year-old Richard Burbage as Romeo. Alexander Cooke was another boy actor who helped bring some of Shakespeare's heroines to life during the plays's first runs.