Margaret Anne Georgiadou started a petition on the UK parliament’s website in late February, calling for Article 50 to be revoked and for the UK to remain in the EU.
It rapidly gained signatures this week after Theresa May appealed to the country and MPs to back her deal.
On Saturday the petition reached over 4.16 million signatures. It has the highest rate of sign-ups on record, according to the official petitions committee.
“In the past 10 hours [I] have had three death threats over the phone, my [Facebook] account has been hacked and had a torrent of abuse on Facebook,” Ms Georgiadou said on Saturday morning.
“Who wants Brexit so much that they are prepared to kill for it?”
The 77-year-old added that she was currently in Cyprus and had deleted her Facebook account following the abuse.
She also said she was unable to attend an anti-Brexit march in London on Saturday, despite being invited.
Organisers of the Put It To The People march estimated that a million people had marched through the capital, making the demonstration one of the biggest ever protests in the UK.
If the estimate is accurate the march will match the size of the anti-Iraq War protest in 2003, when around a million protesters marched through London.
“Please sing March on, march on/With hope in your hearts/ And you’ll never be alone’ for me at the March!” Ms Georgiadou said to protesters in a post on her Twitter account.
At one point this week nearly 2,000 people were signing Ms Georgiadou’s petition every minute.
Signatures continued to be added even after the threat of a no-deal exit on 29 March was removed when EU leaders agreed Brexit could be delayed.
Although conspiracy theories have begun circulating about the petition, the House of Commons petitions committee clarified that 96 per cent of the signatures are listed as from the UK.
They added that overseas signatures were valid, since “anyone who is a UK resident or a British citizen can sign a petition. This includes British citizens living overseas.”
The petition is now the most popular one to ever be submitted to parliament.