It is a sign of the times that one of the earliest and best known robots in movie history should move to the top of the list of the most expensive movie props ever sold. Now that robots have progressed from science fiction to reality, it isn't all that surprising that Robby the Robot's price has surpassed all but one of the most iconic movie props in history.

The complete Robby suit, control panel, his jeep, numerous spares, alternate original "claw" hands, and the original wooden stage shipping crates, were sold yesterday (November 21, 2017 ) by Bonhams in New York for US$5,375,000 including buyers premium.

The only purpose-built movie prop to have ever sold for more is Marilyn Monroe's "subway dress" from The Seven Year Itch (1955) which was sold by Profiles in History for $5,520,000 (inc. buyers premium) in 2011.

Robby the Robot may have first appeared in the 1956 movie Forbidden Planet, but his film and TV appearances number more than 30, including movies such as The Invisible Boy, Phantom Empire and Gremlins, and his TV show appearances included episodes of My Little Margie, The Thin Man, Columbo, The Addams Family, Lost in Space, The Twilight Zone, The Man from U.N.C.L.E., Mork & Mindy, Project U.F.O. and Ark II.

Robby the Robot was also used in a well-known AT&T television commercial in 2006, and was inducted into the Robot Hall of Fame in 2004, so although Robby may look a little kitsch when viewed in an era where Toyota and Honda offer far more advanced robots to the public, he was on the bleeding edge of technological capability at the time he was built by MGM more than 60 years ago.

In 1956, Robby's construction costs reportedly accounted for seven percent of the Forbidden Planet's $1.9 million budget which calculates to $133,000 in 1956 dollars: roughly $1.2 million today.

The full story of the robot is expertly told in the Winter 2017 edition of Bonhams quarterly magazine with the auction description adding more granular detail.

To illustrate the significance of the sale, here's our list of the most expensive movie props ever sold, emphasizing Robby's exalted place among the icons of cinematic history.

The most expensive movie props in history

We have only included two film cars in this listing because there are numerous instances of standard cars being used as movie props which were subsequently to become more valuable in their own right (and we keep a separate list of movie cars) with most of their value deriving from their worth as collectible automobiles.

The Batmobile and James Bond's Aston Martin DB5 are different, at least in our opinion, because they were made specifically as movie props. There's only one Batmobile, and the Aston Martin DB5 was never sold with options such as retractable machine guns and ejector seats.

Similarly, we haven't listed the Vickers-Supermarine Spitfire TR Mark IX which appeared in the 1968 film, Battle of Britain and sold for $2,527,204, because it would have sold for that much even if it hadn't been in the film. Nor have we listed Michael Jackson's $1.8 million red leather jacket worn in Thriller (1983), the most successful music video of all-time (9 million sold), mainly because it wasn't worn in a movie.

As always, we have ordered our listing based on the total price paid by the buyer at auction (including the buyers premium) as opposed to the "hammer price".

1 | Marilyn's subway grate dress from The Seven Year Itch (1955)

Price: $5,520,000 | Auctioneer: Profiles in History

2 | Robby the Robot from Forbidden Planet (1956)

Price: $5,375,000 | Auctioneer: Bonhams

3 | The Batmobile from Batman (1966)

Price: $4,620,000 | Auctioneer: Barrett-Jackson

4 | James Bond's Aston Martin DB5 from Goldfinger (1964)

Price: $4,595,998 | Auctioneer: RM Sothebys

5 | Audrey Hepburn's Ascot dress from My Fair Lady (1964)

Price: $4,400,000 | Auctioneer: Profiles in History

6 | The Maltese Falcon from The Maltese Falcon (1941)

Price: $4,085,000 | Auctioneer: Bonhams

7 | The Piano from Casablanca (1942)

Price: $3,413,000 | Auctioneer: Bonhams

8 | Cowardly Lion Costume from The Wizard of Oz (1939)

Price: $3,077,000 | Auctioneer: Bonhams

- | Dorothy's Ruby Red Slippers from The Wizard of Oz (1939)

Price: approx. $3 million | Sold privately

We've shown the slippers which Judy Garland wore in the movie without an official number because the price cannot be verified. The price was never disclosed but is rumoured to be in the vicinity of $3 million. Actor Leonardo DiCaprio, director Steven Spielberg and other anonymous benefactors purchased the slippers for the Academy of Motion Picture Arts and Sciences museum.

9 | Judy Garland's 'Dorothy' dress from The Wizard of Oz (1939)

Price: $1,565,000 | Auctioneers: Profiles in History

10 | Wardrobe from The Sound of Music (1965)

Price: $1,560,000 | Auctioneers: Profiles in History

11 | Marilyn Monroe's's red sequinned showgirl gown from Gentlemen Prefer Blondes (1953)

Price: $1,476,000 | Auctioneers: Profiles in History

View gallery - 17 images