An estimated jackpot of £12m will be up for grabs in tonight's Lotto draw.
It is only the 28th double rollover in the 15 years of the National Lottery.
A spokesman said: “A £12m jackpot would take the fear out of Halloween and you could be celebrating with your ghostly friends in your new haunted castle.”
The last double rollover winners were Martyn and Sandra White from Luton who scooped £10.7m in April. If not won there will be a triple rollover for only the fifth time.