In the Federation, a cultural observer is a member of an observer team dispatched to a pre-warp civilization for research and assessment. In accordance with the Prime Directive of non-interference, the research is strictly covert. (Star Trek: Insurrection)

John Gill was a cultural observer working without teammates on Ekos in the 2260s. (TOS: "Patterns of Force")

Nikolai Rozhenko was stationed on Boraal II as a cultural observer of the Boraalans in 2370. (TNG: "Homeward")