What title did the Queen give to Prince William and Kate Middleton?
Queen Elizabeth II gave Prince William and Kate Middleton the title "Duke and Duchess of Cambridge."
William also became Earl of Strathearn and Baron of Carrickfergus. This makes Kate the Countess of Strathearn and Baroness of Carickfergus.
Titles including "Cambridge" are usually reserved for the young members of the royal family. The last time there was a Duke of Cambridge was in 1801 by Prince Adolphus and Prince George (his son).