Marsh McLennan has promoted from within to replace longstanding general counsel Peter Beshar, whose nomination to head up the US Air Force's legal team was approved this week by the US Senate. 

The professional services giant has chosen Katherine Brennan – currently general counsel of its insurance broking and risk management arm Marsh – to take over from Beshar, who served as the company's top lawyer for nearly two decades.

Brennan joins the firm’s executive committee and will report directly to the company’s president and CEO, Dan Glaser.

She is tasked with overseeing a team of around 450 individuals spread across the legal, compliance and public affairs function serving Marsh McLennan’s four divisions: insurance broking and risk management firm Marsh, reinsurance firm Guy Carpenter and consulting firms Mercer and Oliver Wyman.

Brennan has worked at Marsh McLennan since 2008 except for a period between 2015 and 2017 when she was deputy general counsel at S&P Global.

She takes up her new role less than a year after being appointed general counsel of Marsh. When she assumed that position, in June 2021, she continued serving as chair of Marsh McLennan’s ESG management committee as well as its enterprise-wide crisis management team.

Glaser characterised Brennan as “a remarkable leader and lawyer” whose “experience leading a range of complex legal, compliance and regulatory matters on behalf of the company makes her the ideal candidate for this role”. 

“We’re fortunate to have a colleague with her knowledge, integrity and commitment poised to take on this critical position,” he added.

Glaser also thanked Beshar for his “leadership and devotion” to Marsh McLennan. 

“Peter has embodied our commitment to advancing good and tirelessly promoted the company’s reputation, helping us grow and thrive. He has also been a champion of ethics, strong and effective governance practices, and environmental and social causes,” Glaser said. “We wish him continued success as he serves the United States at a critical moment.”

Beshar, who joined Marsh McLennan from Gibson Dunn & Crutcher in 2004, began his legal career as an advisor to former secretary of state and Manhattan district attorney Cyrus Vance, who joined Baker McKenzie’s New York office as a partner to lead the firm’s cybersecurity practice in January.

Founded in Chicago just over a century ago, Marsh McLennan employs 83,000 people across more than 130 countries. The company stands as one of the top ten largest professional services firms ranked by market cap, coming in at sixth place behind ADP, Schneider Electric, Infosys, Tata and Accenture.