Ogata Kōan (緒方 洪庵, August 13, 1810 – July 25, 1863) was a Japanese physician and rangaku scholar in late Edo period Japan, noted for establishing an academy which later developed into Osaka University.

Ogata was born in 1810 to a family of low-ranking samurai of Ashimori Domain in Bitchū Province in what is now part of the city of Okayama.

He moved to Osaka in 1825 with his father, and began studies in rangaku and medicine at a private academy run by Naka Tenyū from 1826.

However, Ogata died a few months later in July 1863 of acute hemoptysis, caused by the tuberculosis he had suffered from for many years.

Built in a conventional eighteenth-century style, the students left their mark on the central post of the second-floor classroom, slashing and hacking it with their swords.