'Star Trek' legend William Shatner will pay homage to his friend and co-star Leonard Nimoy in a book about the late actor's life.

Shatner, 84, starred in the iconic sci-fi series as Captain James T. Kirk, opposite Nimoy's half-human half-Vulcan science officer Mr. Spock, and now Shatner is going to honour his ''brother'' in print.

Shatner told The Guardian newspaper: ''I'm writing a book about Leonard. I had a brother, whose life arc was so much like mine that we understood each other completely. Our age, our birth, the same types of problems in our marriages - our careers arced in the same manner. ''

Nimoy and Shatner acted together for seven series set in the 23rd century on the USS starship Enterprise from 1966 to 1969.

Nimoy - who was 83 when he passed away in February this year - went on to star in another hit TV series 'Mission: Impossible'. He also won acclaim in stage shows 'Fiddler on the Roof' and 'One Flew Over the Cuckoo's Nest' in the 1980s.

Shatner added: ''We had a great deal in common, Leonard and I. And thusly we were able to understand each other. I've lost a dear friend.''