The Weeping Angels from the “Blink” episode of Doctor Who (June 9, 2007) instantly became one of the most iconic characters on the show, almost on par with the Daleks and Cybermen. They’ve been pretty popular and referenced in all kinds of other media since then. However, the game Condemned: Criminal Origins did that same concept two years earlier (November 22, 2005). At one point in the game, you investigate a derelict store and come across a bunch of mannequins which move when you turn your back on them.
For the record, SCP-173 was first posted to the /x board on 4chan on June 22, 2007, a couple of weeks after “Blink” aired, clearly inspired by it.
No doubt there have been other similar creatures imagined before the mannequins in Condemned. The concept is hardly unique or extraordinary. Feel free to mention some older ones in the comments.