Catti, Or Chatti, an ancient German people, who according to Caesar lived beyond the Ubii, whose seat was about Cologne, and were divided inland from the Cherusci by a wood which he calls Bacenis. Tacitus states that their country lay between the Rhine and Danube, extending from the Black Forest on the south to what were called the Decumates Agri, a tract of land which paid tithe to the Romans, and lay along the latter river, to the northward. If both statements be accurate, their territory must have been very extensive, including Hesse-Cassel on the north and Baden on the south. Tacitus describes their character, habits, and manner of life as far less barbarous, so far at least as regards their military tactics, than those of the other German tribes. Their force lay in their infantry, whom, besides their arms, they loaded with tools and provisions. They did not allow their young men to cut their hair or trim their beards until they had slain an enemy; and all youths of unusual strength and size were compelled to wear an iron ring until they should have gained the right to remove it by slaying a man in battle. They had no individual property in land or houses, but held everything in common.

The Romans gained many advantages over them under Drusus and under Germanicus, who destroyed Mattium, their chief town, but never wholly conquered them. They are last mentioned as existing toward the close of the 4th century, and afterward disappear among the Franks.