This paper aims at exploring the cultural ambiguity which William Shakespeare remarkably extracts from the sources of his major plays, turning it, eventually, into an essential instrument of the tragic and the tragedy. What in normal/modern circumstances would easily count as “plagiarism”, becomes here, paradoxically, a token of artistic genius and brilliant creation. Our examples will be from the four outstanding tragedies—Hamlet, Othello, King Lear and Macbeth. The sources selected by our research will be Saxo Grammaticus’s Histoires tragiques, Cinthio’s Un Capitano Moro, the Celtic legend Leir of Britain and, obviously, Holinshed’s Chronicles. We shall try to demonstrate that the so-called cultural ambiguity adopts various forms in Shakespeare’s plays, going from the clash of civilisations (Hamlet and Othello) to the crisis of identity (Lear and Macbeth).