Prowse, originally from Bristol and best known for playing the iconic character in the original Star Wars trilogy, died last week at the age of 85.
He provided the physical performance, while James Earl Jones did Vader’s voice.
The figurine was placed on the empty plinth that housed a statue of a slave trader Edward Colston.
This was knocked over and dumped in Bristol Harbor during a Black Lives Matter protest in June.
The 1-foot Vader figure appeared overnight and it’s unclear who is responsible or if permission has been given.
Otherwise, it is unlikely that it will stay put for long.
Since the fall of the statue of Edward Colston, many statues and sculptures have been placed on the plinth.
A sculpture of Black Lives Matter protester Jen Reid was withdrawn after only a day.