Actresses aren't supposed to have cultural impact unless they are more movie star than thespian of theaatuh. Meryl is not movie star/celebrity for obvious reasons. The closest film she has to pedestrian is Devil Wears Prada. (though the GP does randomly stan fror K vs.K alot I've noticed)
I have no idea what Megan Fox looks like. As someone who never watches movies I only know the most famous actresses, like Sandra Bullock and Angelina Jolie.