It may take years to assess responsibility for the still-unfolding global credit crisis, but billionaire investor Carl Icahn is joining a chorus of critics taking aim at $1,000-per-hour corporate directors who failed to hold executives’ feet to the fire.

“What did they do to prevent these great ships from going down?” Mr. Icahn asked on his Icahn Report blog. “Were they enjoying lavish lunches and fine wines in the officers' dining rooms or were they on the bridge challenging the captain? Or was the captain even there?”

Corporate executives and pundits have lashed out at the practices of short-sellers, the failures of credit-rating agencies and the reactive policies of the Federal Reserve and the Treasury Department. Mr. Icahn, however, set his sights on directors who are allied with entrenched management.

Mr. Icahn maintains that the failures at financial firms Lehman Brothers, American International Group, Fannie Mae, Freddie Mac and Merrill Lynch can be traced back to “excessive risk-taking by managements” or failure to understand the risks.

Though he acknowledges that he does not know what went on inside boardrooms, the only rational conclusion is that the boards of directors at a number of “these imploded financial firms utterly failed to successfully implement some of their primary tasks—to oversee management and monitor and evaluate risk controls.”

Mr. Icahn, a frequent critic of boards of directors who stand in the way of his efforts to reform or take control of companies, said that “all too often compliant boards are intimidated by managements in their cushy, well-paid worlds.”

The billionaire investor has grabbed headlines by leading efforts to pressure the management and boards of companies to change management or sell themselves outright. He worked to broker the sale of BEA Systems to Oracle in January, but failed in an effort to arrange the sale of Yahoo to Microsoft.

In his blog, Mr. Icahn cited a study by executive compensation consultancy Steven Hall & Partners that found that director compensation at the largest U.S. corporations is running at more than $1,000 per hour.

“Give the massive bankruptcy filing at Lehman, I would appreciate it if someone would advice me of what those board members did to deserve that compensation?” he said.