Baron Hayashi Gonsuke (林 権助, March 23, 1860 – June 27, 1939) was a diplomat of the Empire of Japan.

In 1867, his grandfather and father were both killed in combat during the Battle of Toba–Fushimi, leaving the seven-year-old Gonsuke as head of the Hayashi household.

While in China, he helped Liang Qichao escape to exile in Japan after the Conservative Coup ended the Hundred Days' Reform.

Hayashi was highly regarded by Katō Takaaki, and was appointed Director of the Communications Bureau in the Foreign Ministry in 1899.

During the Russo-Japanese War, Hayashi served as Deputy Ambassador to the Kingdom of Korea,[1][2] and in that capacity signed the Japan–Korea Treaty of 1904 of February 23, 1904, which gave the Imperial Japanese Army freedom of action on the Korean Peninsula.