Cameca

Cameca was an elderly Aztec woman in the 15th century. Because of her age, she spent most of her time in the Garden of Peace and was often consulted by others for her wisdom. (TV: The Aztecs)

The First Doctor, not understanding the customs of the Aztec empire at the time, unwittingly proposed to Cameca when he shared cocoa with her. She later helped the Doctor and his companions find the secret entrance to the temple, despite knowing it would allow her beloved to leave her. She gave the Doctor her brooch before they parted ways, which he took with him as he entered the TARDIS. (TV: The Aztecs)

Behind the scenes

 * Cameca was the first human woman for whom the Doctor expressed romantic affection. He did not display romantic inclinations on screen again until his eighth incarnation.
 * Margot Van der Burgh, the actress playing Cameca, was much younger than the character was intended to be. She was in her late twenties at the time she played the role. Her character's intended age was accomplished with makeup and speaking in a lower voice.