If the prizes are not claimed within 180 days (around 6 months) of the draw date, they will go to charities. The National Lottery are appealing for players to checks wallets, purses and behind the backs of sofas.
The unclaimed winner in the south west, which was drawn last month (20th February 2018), has a ticket with these winning numbers on: 6, 14, 19, 25, 29 Lucky Stars 5, 11.
Andy Carter, of The National Lottery, said: "We're desperate to find this mystery ticket holder and unite them with their winnings. This amazing prize could really make a huge difference to somebody's life.
"We're urging everyone who bought a ticket in this area to check their old EuroMillions tickets again or look anywhere a missing ticket could be hiding, so that this prize can turn someone into the newest member of the lottery millionaire club.
"Try checking in the pockets of clothing, in wallets, bags and down the back of the sofa."
Full list of unclaimed winners below:
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