The samuhanayok (Thai: สมุหนายก) was one of the two chief ministers in the historical Chatusadom government system of Siam (now Thailand), originally charged with civil affairs but later overseeing both civil and military affairs in northern cities. During the Ayutthaya and Thonburi periods, the official who held the post usually took the noble title of Chakri (Thai: จักรี, RTGS: Chakkri).^[1] The term, from Sanskrit चक्री cakrī, literally meant "one who has a discus", referring to the Hindu god Vishnu who possesses the discus Sudarshana).

The last office-holder to be known by the title Chakri was Thongduang, who established the Rattanakosin Kingdom and became King Rama I in 1782. His dynasty, which includes the current Thai royal family, is known as the Chakri Dynasty after his former title. Later office-holders of Rattanakosin were granted individualized titles.^[1]

Officials who served as samuhanayok included:

• Phraya Chakri, who served under King Mahinthrathirat and was a spy for King Bayinnaung of Burma, leading to the first fall of Ayutthaya in 1569
• Chaophraya Bowonratchanayok (Sheikh Ahmad), who served under King Songtham
• Chaophraya Chakri (Khunnen) (ขุนเณร), who served under King Sanphet IX^{[citation needed]}
• Chaophraya Aphaimontri, who served under King Borommakot^[1]
• Phraya Chakri (Khrut) (ครุฑ), who served under King Borommakot^{[citation needed]}

• Chaophraya Chakri (Mut), usually referred as Chaophraya Chakri Khaek (the 'Muslim Chaophraya Chakri'), who served under King Taksin of Thon Buri. He was a descendant of Suleiman, the sultan of Songkhla
• Chaophraya Chakri (Thongduang), who was also known by the title Somdet Chaophraya Mahakasatsuek (though sources are conflicting).^[1] He served under King Taksin, and later seized the throne, establishing Rattanakosin and becoming King Rama I.

1. Chaophraya Rattanaphiphit (Son): 1782–1805
2. Chaophraya Rattanathibet (Kun): Served under King Rama II.
3. Chaophraya Aphaiphuthon (Noi): Served kings Rama II and Rama III until his death in 1827.
4. Chaophraya Bodindecha (Sing): 1829–1849. He spent most of his term leading war campaigns, and was deputized by Phraya Sisahathep (Thongpheng).
5. Chaophraya Nikonbodon (To): 1851–1863
6. Chaophraya Phutharaphai (Nut Bunyarattaphan): 1863–1878
7. Prince Mahamala, who also held the title Krom Somdet Phra Bamrapporapak: 1878–1886
8. Chaophraya Rattanabodin (Bunrot Kanlayanamit): Held the post from 1886 until its abolition in 1892.^[1]

• List of samuhakalahom
• List of prime ministers of Thailand