Marcus Williamson (born 1965) is a British writer, journalist and campaigner.
In 2009 the AIM-listed (since delisted and failed) spyware company Phorm created a website Stopphoulplay.com to attack Williamson and fellow campaigner Alexander Hanff. The company accused Williamson of "...waging a "serial letter writing" campaign to Phorm's potential customers and partners in attempt to discredit the company and Mr Ertugrul."  The site was soon taken down and later described as a "PR disaster".
He is the editor of the consumer information website CEOemail.com.
He advocates contacting company chief executives (CEOs) as a means of resolving customer service issues and of conducting campaigns. The site was featured in the LifeHacker article "CEOEmail.com Helps You Take Your Issue to the Top When Other Avenues Fail".
- Neate, Rupert (28 Apr 2009). "Phorm chief labels critics 'serial agitators'". The Telegraph.
- Neate, Rupert (1 May 2009). "Phorm's Stopphoulplay site is a PR disaster". The Telegraph.
- "Archived copy". Archived from the original on 16 January 2014. Retrieved 2014-01-16.
- Insley, Jill (14 September 2010). "Nationwide chief executive shuts down email address". The Guardian.