Possible Clues:

• John of "Star Trek Into Darkness"
• John of TV's 'Sleepy Hollow'
• Actor John of 'American Pie' films
• John of "Harold and Kumar Go to White Castle"
• Comical Margaret
• John who played Sulu in "Star Trek" (2009)
• Comedian Margaret or actor John
• Comedy actress Margaret
• Comedian who blogs
• Harry Potter's first girlfriend ___ Chang