William Shatner Remembers Leonard Nimoy: 'I Never Had a Friend Like That'

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William Shatner challenged ET's Brooke Anderson to an arm-wrestling competition in 2011, and on Monday it was time for a rematch.

"I remember that was the first time a lady beat me," Shatner said of his competition with Brooke.

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Brooke remembered it the other way around, so the two squared off again on the ET stage with Kevin Frazier officiating.

The 84-year-old actor's competitive spirit runs deep. His Hollywood Charity Horse Show starts this weekend to benefit local charities including A Place Called Home, Blind Children's Center, BraveHearts Therapeutic Riding & Educational Center and Children's Hospital Los Angeles.

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"[It benefits] many children's charities, veterans charities," Shatner said. "Every cent that comes into us goes out to the kids and to the veterans."

Shatner's late Star Trek co-star Leonard Nimoy also was a big supporter of charities, including the Nimoy Foundation, established in 2003 to support the work of artists through grants. In 2009, Nimoy gushed about Shatner, saying, "I consider him like a brother to me."

"I never had a friend like that," Shatner told ET. "It's a tough one to lose."

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Nimoy passed away in February due to the end stages of chronic obstructive pulmonary disease (COPD). While Shatner didn't really get a chance to say goodbye to his co-star, he revealed that their last correspondence was meaningful.

"I sent him an email at the very end, telling him to be happy," Shatner said. "That he was loved."