AP Photo/Nati Harnik
WPP CEO Sir Martin Sorrell.
For years they have been directing insults at each other through the press and on stage when they appear at public events. Sorrell has described Lévy as the "Freddy Krueger of advertising," for example, while Lévy emailed us last year to say Sorrell is "often acting like a toddler arguing who's got the best Halloween costume."
But what looks like apparent hatred, is probably nothing more than a good old fashioned rivalry. After the Paris terror attacks, Sorrell emailed Lévy to check he was all right, according to a profile of the WPP boss in the Financial Times Magazine.
Lévy said the unexpected contact was "kind and appreciated."
However, looking back at the history between the two business leaders, Lévy said their once-cordial relationship started to "turn to vinegar" when WPP beat Publicis Groupe to acquiring advertising agency Cordiant in 2003.
Lévy told The FT Magazine: "From that moment, there was an animosity on his part that forced me also to be very disagreeable to him. I couldn't accept the nonsense that he talked. Constantly, from that moment, he hasn't missed a chance to be nasty to Publicis or to me, including ad hominem attacks, which are really extremely unpleasant."
The FT Magazine profile paints Sorrell as a workaholic who always plays to win - even his wife, the media and entertainment industries director at the World Economic Forum Cristiana Falcone, says that if he retires she is going to "hire a call-centre with a 24-hour service which keeps pushing emails to keep him busy, because if he is in my house with nothing to do he will micromanage everything."
He does have a softer side - sometimes helping colleagues who are in trouble or gravely ill - but he is also prone to directing bursts of anger at his staff, the FT suggests.
Jeremy Bullmore, the former chair of WPP advertising agency J Walter Thompson, said of those outbursts: "I think it's impatience. He can't understand why people aren't' as quick as he is about anything."
Sorrell's relentless focus has paid off for the business. The company has transformed from a small maker of wire baskets, Wire & Plastic Products, into the world's biggest advertising agency network , with a £20 billion valuation.
And it's also helped Sorrell become the highest paid CEO in Britain: He is set to receive £36 million ($53 million) in share awards this year, on top of £1.1 million ($1.6 million) salary, according to The Wall Street Journal.