William Shatner misses his ''brother'' Leonard Nimoy ''terribly''.

The 87-year-old actor was left devastated when his 'Star Trek' co-star passed away in March 2015 at the age of 83 and admitted he doesn't laugh very often without his friend being around.

He said: ''I miss Leonard terribly. He was the brother I never had. Our lives had similar patterns in terms of marriage, divorce, death, children and the fact our careers took many years to take off.

''He was very, very funny. Sometimes he made me laugh to the point of coughing. I don't cough any more. That laughter is gone - so I miss that more than anything.''

The 'TJ Hooker' star missed Leonard's funeral because he already had a charity commitment and though he's still sad he didn't get to say a final farewell to his pal, he still thinks he made the right decision.

He told the Daily Mirror newspaper: ''I had what you would call a Hobson's choice.

''I had Leonard's funeral to go to, but many months earlier, I had obligated myself to a charity event.

''It was for the Red Cross and there were millions of dollars being raised, partially in my name. So I fulfilled the obligation where I said to the audience, 'Fame is far more fleeting than you think. In days, weeks, certainly months, the ashes are forgotten, great reputations are forgotten. But what does remain is our good deeds. They reverberate until the end of time. And their good deeds that evening will be remembered long after Leonard and I pass'.''

William himself - who has three children with first wife Gloria Rand and married fourth wife Elizabeth in 2001 - feels healthier than ever and believes he's currently busier than ever.

He said: ''I'm the healthiest human being you would ever meet,'' he proclaims.

''I exercise, I eat well and try to think positively. And I say yes to life, yes to opportunities and new ideas, and to the passions of life. I'm more creative than I've ever been. More active, perhaps than I've ever been. And I ride horses competitively all the time.''