He ran Animal Planet and HGTV. Now he will oversee WarnerMedia. Who is David Zaslav?

David Zaslav was at a crossroads in 2007.

After spending 18 years at NBC, where he helped develop a cable portfolio that included CNBC and MSNBC, Zaslav had an offer to run Discovery Networks, the home of documentaries, nature shows and Shark Week.

The company’s programs had once been a favorite of cable system operators, who pointed to them whenever they needed to assuage school boards and local government officials angry over racy music videos on MTV and R-rated films on HBO. But that image was less meaningful as the cable business matured.

“It was not the shiniest object on the block at the time,” recalled Tom Rogers, Zaslav’s friend and former boss at NBC.

Nevertheless, Rogers urged him to take the job at Discovery’s previous home base in Silver Spring, Md., not exactly a show business hub.

“I said, ‘David, absolutely. You’ll have a platform that you can grow,’” Rogers said.

What Rogers knew and others have learned since is that Zaslav, 61, prides himself on being a relentless change agent.

He transformed Discovery from a niche TV service to the largest purveyor of nonfiction programming, creating new channels and franchises, expanding its reach internationally and seamlessly absorbing other popular cable TV brands such as the Food Network and HGTV when it acquired Scripps Networks in 2018 in a $12-billion deal.

The company’s value grew from $5 billion to nearly $22 billion over that time.

Zaslav’s success made him one of the highest paid chief executives of a publicly traded U.S. company (in 2018, he earned a staggering $129.4 million as a result of the Scripps deal).

But he still has the drive and desire to navigate the treacherous terrain of the entertainment industry’s future as overseer of a newly merged entity that would put Discovery Networks and WarnerMedia and assets such as HBO, Warner Bros. Studios, CNN, TLC — the home of “90 Day Fiancé” — and HGTV’s “Fixer Upper” under one roof. The assets would be folded into a new publicly trade company owned by AT&T and Discovery.

The companies formally announced the $43-billion merger, which is subject to regulatory approval, on Monday.

“I’m so excited, but this is really surreal, and just getting it over the finish line,” Zaslav told The Times. “It’s such a historic company and a great set of assets, and it fits so well with what we’ve built over the last 15 years that I’ve been at Discovery.”

Zaslav is known for being energetic and persistent. He does not give up easily.

A year after he took the job at Discovery, Zaslav took notice of how his wife, Pam, was absorbed in the uplifting stories she read in O Magazine, the publication founded by Oprah Winfrey.

Zaslav decided that his sleepy media company needed someone of Winfrey’s stature to boost its profile.

So Zaslav doggedly pursued Winfrey, traveling to her Chicago headquarters. He did something unheard of at the time: In 2008, he offered Winfrey 50% ownership of one of Discovery’s small channels, and they eventually rebranded it OWN: Oprah Winfrey Network.

The network floundered in its early years, but Zaslav stuck with OWN until it found its way as one of the most popular cable channels for women ages 25 to 54.

Zaslav’s patience with Winfrey came from a deep belief in respecting talent. He believes that WarnerMedia shares that value.

“This is a business built on relationships,” Zaslav said. “And I’m old enough to remember that when I started out, if you could spend time with anyone in the business, you’d want to spend time with [Time Warner founder] Steve Ross. He was the guy who gave people the freedom to tell the stories they wanted to tell. He created a lot of value for Warner Bros. He really set the standard for how these businesses should be run.”

But those who work for Zaslav need to be properly caffeinated at all times. He starts his day in New York before 5 a.m. Eastern, and he will have a conference call on a Sunday if he believes it’s necessary.

He brought that kind of urgency to the development and January launch of Discovery’s streaming service, Discovery+, which was seen as essential to setting the company up for the future and key to making it an attractive merger partner.

Zaslav comes from humble roots in Brooklyn and the New York City suburbs. He graduated from Binghamton University, a state school in New York state, and then got his law degree at Boston University.

He is known to be a devoted family man with three grown children, including daughter Ali Zaslav, who works as a reporter at CNN, which will become part of the merged company.

Last year, David Zaslav acquired the 3,900-square-foot Beverly Hills mansion that was home to the late movie mogul Robert Evans (“The Godfather,” “Chinatown”), telling friends he wanted to spend more time in Los Angeles.

While Zaslav has wealth and fancy celebrity friends — his annual summer bash in the Hamptons is a coveted invite among New York’s media set — his essential wardrobe piece is a sleeveless Patagonia vest, usually seen with the logos of one of his networks on it.

Rogers says it likely evolved from Zaslav’s days having to woo cable operator to carry NBC’s channels. “He would put the network on anything,” Rogers said. “He really liked tchotchkes.”

When the name of the newly merged Discover-WarnerMedia entity is presented next week, expect it to show up on Zaslav’s vest.

“There was a time when I used to wear Patagonia clothes, but that was before I met David and surrendered as it became clear I had neither the volume nor variety to out-vest him,” said filmmaker Steven Spielberg, who is a friend.