Final answer:
In Shakespeare's 'Macbeth', King Duncan names Malcolm as the heir to the Scottish throne, with the title Prince of Cumberland. Historically, James VI of Scotland became James I of England in 1603 after Elizabeth I's death. Today, Prince Charles is the heir to the British throne, followed by Prince William.
Step-by-step explanation:
The heir to the Scottish throne is traditionally the eldest child of the reigning monarch. In a historical context, upon the death of Elizabeth I in 1603, James VI of Scotland ascended to the English throne as James I, uniting the two crowns. In William Shakespeare's Macbeth, King Duncan names his eldest son, Malcolm, as his heir, also bestowing upon him the title Prince of Cumberland. In a more contemporary context, after the passing of Queen Elizabeth II, her son Prince Charles would ascend to the throne. Subsequently, if Prince Charles were to abdicate or predecease without reigning, Prince William would become the heir apparent.