To the business world, Matthew A. Rosen was a powerhouse, working deals for companies as big as Yahoo!, Discovery Holding, and RJR Nabisco.

To the theater, the New York City tax attorney who loved burying his head in numbers was an eager patron, attending shows nearly every night, even amid meetings and business obligations.

But to those who knew him best, he was a family man - one who worked tirelessly - but who, when his kids were growing up, never missed cheering for a son at baseball games or shopping with his daughter for produce every weekend.

Mr. Rosen, 63, a prominent tax attorney born in South Philadelphia, died Friday, Nov. 20, after a 10-month battle with pancreatic cancer.

Originally from the East Passyunk Crossing area of Philadelphia, Mr. Rosen grew up in a family of doctors and lived atop his parents' podiatry practice. But as a young adult, he hated the idea of practicing medicine.

Instead, he studied at Boston University Law School and New York University Law School after graduating from Swarthmore College in 1973. In 1979, he joined the high-profile New York law firm Skadden, Arps, Slate, Meagher & Flom as part of what he called his "one-year plan."

But that one-year plan somehow became 36 one-year plans, Mr. Rosen often joked, as he rose through the ranks of the company, eventually becoming a co-head of the firm's tax practice.

There, he handled multiple aspects of tax work - everything from foreign investments to joint ventures - for big-name clients, including RJR Nabisco during its historic takeover battle in 1988. It was on that deal, his niece Stefani Graff said, that Mr. Rosen "really started to gain notoriety."

So much so, in fact, that he was featured in the best-seller about the RJR Nabisco case, Barbarians at the Gate, which described him as "a lawyer from the thirty-something crowd: Italian suits, tasseled loafers, an office crammed with modern art."

Beyond gaining notoriety in New York City, Mr. Rosen was also ranked by several magazines as one of the top lawyers in his field. Best Lawyers, a legal peer-review publication, named Mr. Rosen its "2013 New York City Tax Lawyer of the Year." He was also recognized in Euromoney's Guide to the World's Leading Tax Lawyers.

Adept and analytic as he was in his job, family members and colleagues said, Mr. Rosen was most passionate about taking care of those around him. He was regarded by his company as one its foremost mentors, "always supporting new talent and the expansion of the practice into new spheres," according to a statement released by the firm.

Outside work, family members said Mr. Rosen loved to travel, and he often spent summers vacationing around the world with his family. Back in the city, while often busy with work, he always made time for family, said Mr. Rosen's niece Tammie Rosen.

"He might be at a bar mitzvah and running to take calls outside," Tammie Rosen said. "But the next thing you knew, he was back inside, with everyone around him, dancing."

Mr. Rosen is survived by his wife, Mariana Elder; his three children, Amanda, Oliver, and Anthony; his former spouse, Diane Rosen; and his brother, Dr. Kenneth Rosen.

Services are to be Monday, Nov. 23, at 1 p.m. at Central Synagogue, 652 Lexington Ave., New York.

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