In King Lear, the Duke of Cornwall’s wife is Regan, one of King Lear’s three daughters. She is the middle daughter, between the elder Goneril and the youngest, Cordelia, and she becomes one of the play’s principal forces of cruelty and political disorder.
At the opening of the tragedy, Regan joins Goneril in flattering Lear so that he will divide his kingdom between them. After Lear gives away his authority, Regan proves unwilling to house him unless he surrenders most of his knights and attendants. Her rejection helps drive the aging king into the storm, where his political collapse becomes a profound personal and philosophical crisis.
Regan’s marriage to Cornwall also links her directly to the play’s most brutal episode. When Cornwall orders Gloucester’s eyes to be put out, Regan encourages the violence and kills a servant who tries to intervene. Cornwall is mortally wounded during the struggle, leaving Regan a widow.
Regan later competes with Goneril for Edmund’s attention. Their rivalry ends when Goneril poisons her. The names are easy to confuse because both sisters oppose Lear and both pursue Edmund, but Goneril is married to the Duke of Albany; Regan is Cornwall’s wife.