Longtime Sports Illustrated NFL writer Paul "Dr. Z" Zimmerman died Thursday at age 86, Peter King of NBC Sports reported.

Zimmerman earned the nickname Dr. Z from managing editor Mark Mulvoy for the analytical approach he took to breaking down NFL games during his time with Sports Illustrated. Prior to his time at Sports Illustrated, he briefly played college football at Stanford and Columbia. He also covered the Jets for the New York Post, and during that time he feuded intermittently with quarterback Joe Namath.

In 1984, his book The New Thinking Man's Guide to Pro Football was published, and it proved to be one of the most defining works of one of the most legendary writers in the sport's history.

During a career that spanned 55 years, Zimmerman spent nearly 30 of those at Sports Illustrated. He covered NFL greats from Vince Lombardi to Joe Montana until his career came to a halt in 2008.

During Thanksgiving weekend of that year, Zimmerman suffered a series of three strokes that left him largely unable to speak and confined him to a wheelchair for the remainder of his life.

In 2016, The MMQB paid tribute to Zimmerman's legacy during Dr. Z Week, when SI republished a number of Dr. Z's best stories.

At the time of his strokes, Zimmerman was working on an autobiography titled Dr. Z: The Lost Memoirs of an Irreverent Football Writer that was published in 2017.

Additionally, NFL Films supervising producer Ken Rodgers put together an Emmy-winning film called "Yours Truly, Dr. Z" that chronicled Zimmerman's life after the strokes.

He is survived by his wife Linda, who he was living with in Noblesville, Ind, two children from his first marriage to Kate Hart, Michael and Sarah, and a granddaughter, Natasha Mariner. Zimmerman also leaves behind Linda Zimmerman's two children Nathan Bailey and Heather Snopek and their families.