Cuauhtémoc (also Cuauhtemotzin or Guatimozin; also written Cuauhtemoc without the diacritical mark) was the last Aztec ruler (Tlatoani) of Tenochtitlán and the last "Aztec Emperor". The name means "descending eagle", from Nahuatl cuauhtli (eagle) and temoc (descent); by extension it can be interpreted as "setting sun".

He lived c. 1502 - February 26, 1525. Cuauhtémoc took power in 1520 as successor of Cuaitláhuac and was a nephew of the emperor Moctezuma II, and his young wife was one of Moctezuma's daughters. He ascended to the throne as his city was being besieged by the Spanish and devastated by an epidemic of smallpox. He was about 18 years of age at the time. Probably after the killings in the main temple, there were few Aztec captains available.

On August 13, 1521, Cuauhtémoc went to call for reinforcements from the countryside to aid the falling Tenochtitlán, after eighty days straight of urban warfare against the Spanish. He was captured while crossing Lake Texcoco in disguise, he surrendered to Hernán Cortés in the Tlatelolco section of Tenochtitlán, with that the great Aztec civilization came to an end.

Cuauhtémoc was tortured by having his feet put to a fire, but even so refused to divulge information about the treasures the Spanish coveted. Cortés eventually ordered him hanged on 26 February 1525, on his trip to Honduras. Cortés proabably took Cuauhtémoc with him so he wouldn't have to kill him close to his fellow Aztecs.

The modern-day Mexican town of Ixcateopan in Guerrero state is home to an ossuary purportedly containing Cuauhtémoc's remains.

Many places in Mexico are named in honour of Cuauhtémoc. These include Ciudad Cuauhtémoc in Chihuahua and the Cuauhtémoc borough of the Mexican Federal District. There is also a Cuauhtémoc station on the Mexico City metro.

Cuauhtémoc is also the name of a training ship belonging to the Mexican Navy.