Martin Droeshout's engraving appeared as the frontispiece of the First Folio of Shakespeare's collected plays, which normally would indicate that it is a picture of the poet. But several clues point to the face being a mask -- and a parody. In this portrait, as sometimes both in Shakespeare's works and in celestial phenomena, appearance is not reality.
The curved line running down from the left ear and under the chin is the edge of the mask, and not an earring as some would have it. The head has two right eyes, a disfigured ear, a mustache growing out of one nostril, a head disproportionately large compared to the torso, and a hydrocephalous and falsely illuminated forehead that spoofs Shakespeare's intelligence. The collar conforms to no known style, the visible tunic has the front and the back of the same left arm, and the entire assembly rests too high upon the shoulders, as if the subject had an inordinately long neck. It appears as if the assembly rests upon the real subject's head, which is facing away from the viewer and into the page that depicts it. This interpretation is supported by the upward curve of the back of the collar that allows the subject to peer out from under the contraption.
This interpretation is supported also by the encomia following the frontispiece. Ben Jonson knew the identity of the poet and wishes that Droeshout had depicted him as well in brass as "he hath hit [hid?] his face," but since he did not, he advises readers to "look not on his picture, but his book." He would not so advise if the picture were a true representation. Further, the editors of the 1st Folio advise that we read him again and again, and "if then you do not like him, surely you are in some manifest danger not to understand him."
An author "J.M." (probably John Mabbe) has the last word. To paraphrase, he writes, "We wondered, Shake-speare, that you [died] so soon." I suspect that this refers to "Shake-speare" having died variously in the 17 years from 1558 to 1574 (see the "Winter's Tale" page previous to this.) He writes further that "An actor's art can die and live to act a second part." The second part refers to "Shake-speare's" poetics, compared to the first part comprising his other skills to which we have alluded on the Home page of this site. Finally, it is probably no coincidence that Leonard Digges the Younger was invited to contribute to the testimonials, and if he and the other contributors were intent on praising Shakespeare, surely they would not have printed his name in a different font and misrepresented hyphenated as "Shake-speare."