John Gentry, a longtime advertising executive and the chief executive officer of supply-side platform OpenX, died Wednesday evening after a long battle with cancer. He was 58.
A post to Gentry’s LinkedIn profile Thursday evening read: “If you are reading this, it means that I’m no longer around and lost my fight with cancer. While I am dying earlier than most, I outlived myself by 28 years, thanks to a kidney transplant and modern medicine, and I’ve had a wonderful life. I am a lucky and thankful man.”
Gentry went on to express gratitude for the many people he bonded with during the course of his career, saying “the best part of the ride has been all the amazing relationships I’ve formed over the years.”
The company confirmed his death in an email to ADWEEK.
Gentry was considered a trailblazer in adtech, contributing to the innovation of header bidding in the mid-2010s and the evolution of supply-side identity technology.
He was also a thoughtful leader, collaborator, and friend to many.
“JG’s belief in me changed my life,” OpenX president Matt Sattel said in a statement shared with ADWEEK. “He was more than a leader to me. He was an advocate, a mentor, and a friend. JG believed that doing the right thing and building a strong business could go hand in hand, and showed us that it was possible to lead with both strength and humanity, even when it was hard. In challenging moments, he pushed me to think bigger, act with clarity, and put our people first. His career and lessons will stay with me always, and he will be deeply missed.”
A graduate of Northwestern University’s Kellogg School of Management and of UCLA, Gentry worked at the Walt Disney Company in the 1990s, where he directed distribution strategy for ABC cable networks. He went on to hold various executive roles across the advertising and financial services industries, with stints as a senior vice president and general manager at Overture (an early leader in digital advertising acquired by Yahoo for $1.63 billion in 2003), chief revenue officer of financial services company Green Dot, and president of adtech startup Spot Runner—before joining OpenX in 2012.
Gentry was appointed chief executive at OpenX in 2020, after years of serving the company as an advisor, and later, as its president. He steered OpenX through various hurdles, including the disruptive entry of header bidding, evolving privacy regulations, and an ongoing legal battle with Google over antitrust allegations.
Gentry’s mentorship and leadership style were widely praised. Chris Gaglia, a former OpenX employee, recalled Gentry’s initial hesitance to hire him over concerns that Gaglia was a surfer, and Gentry was “worried about motivation.” However, the two bonded quickly and, “as it turned out, JG loved paddleboarding and spending time in Newport Beach—and once we connected, we never looked back,” Gaglia said.
“Every once in a while, you meet someone who leaves a lasting imprint on your life. JG was one of those people,” Gaglia said. “Although my time working with him was far too short, I’ll never forget our weekly one-on-ones—half nervous, half excited—because he was always direct, always expected outcomes, and yet somehow always sent you away sharper than when you walked in. He was a leader who challenged you, believed in you, and made you better. The industry lost a great one.”
Michael Todd, an executive at Silver Lake Partners who previously worked as chief technology officer and at OpenX, remembered Gentry as a thoughtful and caring presence. “John was instrumental in building OpenX into the independent, people-first ad tech company it became known for over the past decade,” Todd told ADWEEK. “He combined deep industry intuition with genuine care for those around him, and he pushed everyone to operate at a higher standard. I was fortunate to learn from him as a leader and to know him as a person.”
Tributes to Gentry flooded social media following the news of his death.
Jason Fairchild, cofounder and CEO of TV adtech firm tvScientific, in a post, called Gentry “an industry leader, a pioneer, a collaborator to many of us, and an incredible executive.” He also characterized Gentry as his “best friend,” “mentor,” and “biggest fan.”
Fairchild and Gentry worked together at software firm GoTo.com before Fairchild recruited Gentry to join OpenX. Under his oversight, Fairchild wrote, “OpenX re-transformed into a high-growth company driven by innovation and incredible execution.”
In a statement to ADWEEK, Fairchild added: “John was a force of nature. A force centered on doing the right thing. The right thing for the company and the right thing for the individual. The force was uncompromising and often pushed people out of their comfort zones, but it was grounded in empathy and care for the person.”
In their personal lives, Gentry and Fairchild were extremely close. “We spent countless hours together commuting, vacationing, and just hanging out, talking about work, life’s ups and downs, our goals, family, and whatever was going on,” Fairchild wrote in his post. “We raised our kids together, sharing Christmas mornings or teaming up against the kids for epic Call of Duty matches, only to get our asses kicked by 8-year-olds. We were in and out of each other’s chaotic daily lives for decades. He was the first friend I’d call with good news or to talk through a life challenge.”
Gentry’s selflessness and good nature were echoed by others who knew him and worked with him.
“JG was a thoughtful man that helped me out on numerous occasions without asking for anything in return,” said Wayne Blodwell, who leads the programmatic practice at Stagwell agency Assembly Global, and previously consulted for OpenX. He added: “His openness and kindness will be missed by those around him and the wider industry.”