Sophia von Mengden (1760–1848) was a major Latvian landowner. She was the daughter of George Friedrich von Plettenberg and Elisabeth Benigna von Hohen-Astenberg, and married Gotthard Johann von Mengden (d. 1786) in 1779.After the death of her spouse, she became a major landholder with residence in Mitau. She is regarded to have been one of the more significant landowners in Latvia of her time. She moved to London in 1813.