Leonard Nimoy Dead -- Lived Long, Prospered ... Dies from COPD

Leonard Nimoy, who famously played Mr. Spock, died at home Friday morning in Bel-Air... after battling chronic obstructive pulmonary disease.

The "Star Trek" star announced last year that he was battling the disease and attributed it to years and years of smoking. He had given up the habit 30 years ago.

TMZ broke the story ... Nimoy checked into UCLA Medical Center last week for intense chest pains -- but was eventually released.

Nimoy started playing Mr. Spock when the TV show debuted in 1966 ... and is the only actor to appear in every episode of that original series. He continued in the Spock role through most of the movies -- including the most recent reboot in 2013.

Aside from acting ... Nimoy also wrote books of poetry, 2 autobiographies, and even recorded albums ... mostly cover songs.

Nimoy tweeted for the last time on Feb. 22, saying ... "A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP"

He was 83.

The Trekkie In Chief, President Obama released a statement saying ... "Long before being nerdy was cool, there was Leonard Nimoy ... I loved Spock."

Nimoy's longtime co-star William Shatner tells us, "I loved him like a brother. We will all miss his humor, this talent, and his capacity to love."