Marilyn Monroe's Wig to Hit Auction Block

Marilyn Monroe's blonde wig from her last film, "The Misfits," is about to hit the auction block.

It's the first time in almost 2 decades the mop's been up for grabs. Bidding starts at $10k ... a lot less than the $29.9k it sold for last time around. Heritage Auctions, which is running the show, is counting on $20k minimum.

A lock of Lennon's hair sold for $35k earlier this year ... almost certainly more than MM's fake hair will fetch.

Marilyn's wig has some extras, like 5 ringlets for volume. You also get the original storage box labeled: "United Artists Corporation / The Misfits / Mapes Hotel / Reno, Nevada" and "Hold At Airport For Pick Up" ... so, cool piece of movie history.

Bidding starts Nov. 12.