Watanabe Kazan (渡辺 崋山, October 20, 1793 – November 23, 1841) was a Japanese painter, scholar and statesman member of the samurai class.

He was born Watanabe Sadayasu in Edo (now Tokyo) to a poor samurai family, and his artistic talent was developed from an early age.

Watanabe himself served the lord of Tahara as a senior councilor, one of his achievements being said to be protecting the domain from even a single death from starvation during the Tenpō famine.

On the one hand, he was a traditionalist Confucian, who believed in filial piety and loyalty to his daimyō, and on the other he was enthusiastic about Western ideas regarding science and politics.

Due to the political turmoil involved in this, Watanabe committed ritual suicide (seppuku) as a way to amend for the embarrassment he caused his lord.