Baron Plato Grigorievich Ustinov (Russian: Платон Григорьевич Устинов) (1840–1918) was a Russian-born German citizen and the owner of the Hôtel du Parc (Park Hotel) in Jaffa, Ottoman Empire (now Israel).
Ustinov was born in Russia, younger brother of Mikhail Grigorievich Ustinov, son of Grigori Mikhailovich Ustinov (1803 - 1860) and wife Maria Ivanovna Panshina, paternal nephew of Mikhail Mikhailovich Ustinov (1800 -) and Adrian Mikhailovich Ustinov (1802 -), paternal grandson of Mikhail Adrianovich Ustinov (1775 - 1836) and wife Varvara Guerassimovna Ossorgina (- 1808) and great-grandson of Adrian Mikhailovich Ustinov and wife.
He was a Russian nobleman who held a manor estate in Ustinovka (Устиновка) in today's Balashov Raion. He travelled to the Levant after his doctors recommended its climate to heal his lung disease. On his way there, he met Peter Martin Metzler (1824–1907) and his wife Dorothea, née Bauer (1831–1870), who both worked in Jaffa as Protestant missionaries for the St. Chrischona Pilgrim Mission . The couple earned their livelihood through several enterprises, including a steam mill, a pilgrim hostel, and trading in imported European merchandise. From mid-1861 until early 1862, Ustinov stayed in the Metzlers' hostel, eventually becoming a financial partner in their enterprises. Once his lung disease was completely cured, he returned to Ustinovka, but left the Metzlers a considerable sum of money to enable them to establish a missionary school and an infirmary in Jaffa.
In May 1862, the Metzlers opened a new infirmary and informed the head of the St. Chrischona Pilgrim missionaries in Riehen, near Basel. The missionaries were very pleased about this progress and sent two deaconesses from the Riehen deaconesses' mother house to serve at the infirmary. Ustinov returned to Jaffa in September 1865 and was pleased with the Metzlers' investment of his funds.