Kosa Pan (Thai: เจ้าพระยาโกษาธิบดี (ปาน), RTGS: Chao Phraya Kosathibodi (Pan); 1633 – 15 November 1699) was a Siamese diplomat and minister who led the second Siamese embassy to France sent by King Narai in 1686. He was preceded to France by the first Siamese embassy to France, which had been composed of two Siamese ambassadors and Father Bénigne Vachet, who had left Siam for France on January 5, 1684.
Phutthayotfa Chulalok (born Thongduang; 20 March 1737 – 7 September 1809), posthumously honoured as King Phutthayotfa Chulalok the Great, also known by his regnal name Rama I, was the founder of the Rattanakosin Kingdom (now Thailand) and the first King of Siam from the reigning Chakri dynasty. He ascended the throne in 1782, following the deposition of King Taksin of Thonburi. He was also celebrated as the founder of Rattanakosin (now Bangkok) as the new capital of the reunited kingdom.
Rama I, whose given name was Thongduang, was born from a Mon male line descent family, great-grandson of Kosa Pan. His father served in the royal court of the Ayutthaya Kingdom. Thongduang and his younger brother Bunma served King Taksin in wars against the Burmese Konbaung dynasty and helped him in the reunification of Siam. During this time he emerged as Siam's most powerful military leader. Thongduang was the first Somdet Chao Phraya, the highest rank the nobility could attain, equaled to that of royalty. In 1782, he took control of Siam and crowned himself as the monarch. The most famous event in his reign was the Burmese–Siamese War (1785–1786), which was the last major Burmese assault on Siam.
The Siamese embassy to France in 1686 was the second such mission from the Kingdom of Siam. The embassy was sent by King Narai and led by ambassador Kosa Pan. This embassy was preceded by the First Siamese Embassy to France, composed of two Siamese ambassadors and Father Bénigne Vachet, who had left Siam for France on January 5, 1684.