Ottawa is a village in and the county seat of Putnam County, Ohio, United States. The population was 4,367 at the 2000 census.
In 1792 Major Alexander Truman, his servant William Lynch and guide/interpreter William Smalley were sent by George Washington on a peace mission. Truman and Lynch were killed; Truman was apparently killed prior to April 20, 1792 at what later became Ottawa, Putnam County Ohio. A similar mission under Colonel John Hardin also ended in Hardin and his servant Freeman being murdered in Shelby County.
Among the early settlers of the Ottawa area was Henry Kohls, who arrived in 1835 and settled with his family in the village of Glandorf. In the early 1900s, his grandsons, Charles and Frank, were each elected Putnam County treasurer in successive two year stints. Notably, while serving as treasurer they each appointed the other as their chief deputy.