Simon Morris, one of the founders of 365 Corporation, has left the troubled internet media and telecoms company.
Mr Morris, the company's marketing director, left Chris Evans's Ginger Productions to set up the business with Dan Thompson and Danny Kelly in 1997.
He has left "to pursue other interests" and is understood to be working on a number of consultancy projects.
The news comes less than three months after 365's chief executive, Dan Thompson, said he was quitting the company, leaving the business in the hands of Martin Turner and Nik Philpot.
Mr Thompson and Mr Morris were key figures in the consumer wing of the group, while Mr Philpot and Mr Turner championed the more profitable telecoms side of the business.
Mr Kelly, a former TV presenter and magazine editor, is the only co-founder remaining at the company.
But his future is also in doubt. As publishing director, Mr Kelly is in charge of content on 365's websites, many of which face are facing the axe as the company focuses on its telecoms division.
Sources close to the company suggest 365 will pull the plug on Music365 at the end of this month.
Other sites set for the chop include Laughs365, Trivia365 and footy365, which is expected to be merged into Football365.
Since Mr Morris, Mr Kelly and MR Thompson set up the business four years ago, 365 has evolved from a digital content business to a telephony/technology hybrid.
The company's latest project is Eckoh.com, a "voice portal" that uses telephony and web technology to organise people's lives.
Mr Morris was previously managing director at Ginger Productions. Before that he was consumer/programme marketing director at BSkyB and marketing director of Sega UK.
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