Karo is also a town in Chad.

A Karo (家老, house elder) was a top-ranking samurai official in service to a daimyo in feudal Japan.

In the Edo period, the policy of Sankin Kotai required each daimyo to place a karo in Edo and another in the han homeland. The karo in the han was called the jodai karo (城代), while the one in Edo was called the Edo karo (江戸家老).

As an example, the last Asano daimyo of the Ako han was Asano Naganori. While he was in Edo, he was sentenced to commit seppuku for the offense of drawing a sword against Kira Yoshinaka in Edo Castle. When the shogunate abolished the Ako han, all the samurai became ronin. Oishi Kuranosuke, the jodai karo, led 46 other ronin in a vendetta against Kira. As a result of his leadership in the Forty-seven Ronin affair, Oishi went down in history as the most famous of all karo.

The shogunate had a post named roju, the equivalent of karo.

The word karo often follows the honorific prefix go- in the expression gokaro. Similarly, by rendaku, the pronunciation often becomes garo after a word like Edo or jodai.