Actual costumes used in the Star Trek films, including Scotty's jacket, a replica Millennium Falcon from Star Wars and remote control Daleks are among the lots in the unusual collection.
The diverse and valuable haul was once owned by a husband and wife, who build it up using their ill-gotten gains.
The 55-year-old woman from West Yorkshire pleaded guilty in December last year to stealing £2.3 million from her employer, a Halifax-based firm that supplies commercial laundry equipment, over a seven year period between 2005 and December 2012.
Her 48-year-old husband pleaded guilty to laundering £924,190 of the stolen cash, between July 2009 and December 2012.
As well as the huge collection of sci-fi memorabilia, they bought a £500,000 house, spent almost £194,000 on holidays, and £85,947 on a Mercedes car each.
On instructions from West Yorkshire Police, Wilsons Auctions in Northern Ireland is putting the collection up for sale tonight with no reserve price on any of the items.
Aidan Larkin, assets recovery manager at Wilsons, said the auction presented a "once in a lifetime" opportunity for sci-fi fans.
"These items come round very, very rarely," he said. "It's rare for such a large, significant collection of these items to become available. Normally at the specialist toy auctions there are one or two items of a certain range - we have complete waves of toys that were produced."
Mr Larkin, who said he expected a lot of on-line bids from the US, said the set of six Star Trek costumes were probably the most valuable items for sale.
"We have been informed when the costumes last changed hands in Christie's Auctions in New York a few years ago the couple in question spent 27,000 US dollars on these costumes," he said.
The auction gets under way at 6.30pm in Wilsons' headquarters in Mallusk in north Belfast.