Many of Shakespeare’s characters exhibit behaviors that we would consider symptomatic of the condition now known as attention deficit/hyperactivity disorder (ADHD). This chapter considers the ways in which traits associated with ADHD serve as sites of untimeliness and inappropriateness that drive much of the humor, conflict, and narrative tension we see in Shakespeare. Just as the diagnostic process for ADHD relies not on the subjective experience of the individual but rather on whether their behavior is considered “appropriate” for a particular context by those around them, the same behaviors in Shakespeare’s characters are initially tolerated or even celebrated, but ultimately condemned, when changing demands of plot and genre render those behaviors no longer acceptable. By examining how combinations of various traits associated with ADHD correspond to the characteristics assigned to the four humors in the early modern period, we see how certain types of “ADHD characters” frequently occupy particular roles within Shakespearean genres.