Sir Ian McKellen was hit hard by the death of his close friend and collaborator, Sir Patrick Stewart … mourning the loss of a legend.

Ian remembered his friend saying, “He wore his heart on his sleeve, which made him a man to rely on, to admire and in my case, love.”

The ‘Lord of the Rings’ star remembered meeting Patrick “half a century ago” … however, his first strong memory of his friend was warning him not to take his now iconic ‘Star Trek’ — believing it would put his prestigious stage career at risk.

Ian went on to express gratitude on behalf of the “Trekkies” and “film and theatre audiences” who were able to marvel at his late friend’s talents.

The iconic actors’ friendship spans decades — they both starred in “X-Men” together back in 2000.

Ian even officiated Patrick’s wedding to Sunny Ozell in a Mexican restaurant back in 2013.

Patrick previously recalled the sweet, spontaneous ceremony on “Jimmy Kimmel Live!,” saying … “We learned that [McKellen] could not use his [ministry] credentials in Nevada, which is where we were getting married … so we invited Ian and two of our guests and a [theater] director to a Mexican restaurant for dinner.”