NEW YORK (Ticker) -- Hall-of-Fame pitcher Jim "Catfish" Hunter died today after a battle with Lou Gehrig's disease. He was 53.

The disease, called Amyotrophic Lateral Sclerosis or ALS, plagued Hunter in the last year of his life.

Hunter earned a place in baseball history by becoming the game's first multi-millionaire free agent, signing a five-year, $3.75 million deal with the Yankees on New Year's Eve 1974.

The anchor of the Oakland Athletics pitching staffs of the 1970s, Hunter was honored by the team before a June 12 game.

But on August 10, Hunter fell and hit his head on concrete steps outside his home in Hertford, North Carolina, last month and was hospitalized.

Hunter, who recorded 224 victories in a 15-year career with the Kansas City-Oakland A's and New York Yankees, was diagnosed with ALS in November after undergoing tests at Johns Hopkins Hospital in Baltimore.

ALS is a rare and fatal disease that attacks nerves in the spinal cord and brain. The disease manifests itself in muscle weakness and loss of motor skills and leads to paralysis and, ultimately, death. The disease is named for its most famous victim, Yankees Hall of Famer Lou Gehrig, who died of the ailment in 1941 at age 37.

Hunter pitched a perfect game for the Athletics on May 8, 1968 against Minnesota. He won at least 20 games every year from 1971-75 and helped the Athletics to three straight World Series titles beginning in 1972.

An eight-time All-Star who relied primarily on pitch location and changing speeds, Hunter saved his best peformances for big games. He was 4-0 with a save in World Series games for the Athletics.

After winning a career-best 25 games in 1974, he was freed from his contract when an arbitrator determined Oakland owner Charles Finley had violated terms of the deal.

Hunter won 23 games in 1975, his first season in New York, and the following season helped the Yankees to their first World Series appearance since 1964. While arm trouble began limiting his effectiveness, he was a member of the Yankees' back-to-back World Series championship teams in 1977-78.

"Catfish Hunter was the cornerstone of the Yankees' success over the last quarter century," said Yankees owner George Steinbrenner, who signed Hunter to the landmark free agent deal. "We were not winning before Catfish arrived, and since his arrival in 1975 the Yankees have the best record in baseball, as well as four world championships. He exemplified class and dignity and he taught us how to win."

Hunter retired after the 1979 season with a 224-166 record and a 3.26 ERA and was elected to the Hall of Fame in 1987.

The Athletics' tribute to Hunter was used to raise money for ALS, donating a portion of the proceeds to the "Catfish" Hunter Foundation.

"Jim 'Catfish' Hunter holds a very special place in the history of the franchise," said Athletics president Mike Crowley. "On the surface, most will point to his accomplishments on the field. That doesn't do justice to his legacy. Those who played with him point to his leadership and work ethic. Those who knew him will point to his genuine, down-to-earth nature."

"As someone who has been with the organization for the past 32 seasons, I can say that he was my favorite all-time player and he was the classiest individual," added Athletics equipment manager Steve Vucinich.