Count Hayashi Tadasu, GCVO (林 董, 11 April 1850 – 10 July 1913[1]) was a Japanese career diplomat and cabinet minister of Meiji-era Japan.

Hayashi returned home in the midst of the Boshin War of the Meiji Restoration, and joined with Tokugawa loyalists led by Enomoto Takeaki, whom he accompanied to Hokkaidō with the remnants of the Shogunate Army and its Navy.

He was captured by the Imperial forces after the final defeat of the Republic of Ezo at the Battle of Hakodate and imprisoned in Yokohama.

[4] Released in 1871 by Kanagawa governor Mutsu Munemitsu, he was recruited to work for the Meiji government in 1871, and because of his language abilities and previous overseas experience was selected to accompany the Iwakura Mission to Europe and the United States in 1871–1873.

[3] Being a member of the Iwakura Mission in Britain, he was instructed by Yamao Yozo to arrange appointment of the teaching staff for the Engineering Institution (Japan) in the end of 1872.

While serving in London from 1900, he worked to successfully conclude the Anglo-Japanese Alliance and signed on behalf of the government of Japan on 30 January 1902.