Caeso or Kaeso is a Latin praenomen, or personal name, usually abbreviated K. Although never a common name, Caeso was regularly used by a number of prominent families, both patrician and plebeian, during the period of the Roman Republic. The feminine form is Caesula (also spelled Cesula, Caesulla, Caesilla, and Caesillia). The name also gave rise to the patronymic gens Caesonia. Kaeso is the older spelling, dating from the period when the letter K was still frequently used before the vowel A in Latin, and before the letters C and G were differentiated.
The praenomen Caeso was regularly used by the patrician gentes Fabia and Quinctia during the 1st centuries of the Republic, and also by the plebeian gentes Atilia and Duilia (both of which may originally have been patrician). It is also found in the gentes Acilia, Fabricia, and Latria, and must once have been used by the ancestors of gens Caesonia. Its use gradually declined throughout Republican times, and seems to have fallen out of use around the 1st century AD.