Bryan Randall Remembered by 'Yellowstone' Actor Josh Holloway: 'My Brother'

The 'Yellowstone' and 'Lost' star posted a photo tribute to Sandra Bullock's late partner.

Sandra Bullock's longtime partner, Bryan Randall, died on Saturday after a private battle with ALS, and in the wake of his tragic death at age 57, actor Josh Holloway is remembering his friend. The Yellowstone actor posted a photo on Instagram of the two smiling and holding the fish they caught.

"My friend, my brother, my fishing buddy, I love you bro," the Lost star captioned the pic. "Thank you for the good times. Rest in Peace.♥️"

According to PageSix, Bullock kept her support group small to maintain privacy amid Randall's health issues. The group reportedly included her The Proposal co-star, Ryan Reynolds, Holloway and his wife, Yessica.

ET spoke with Dr. Jeffrey Rosenfeld, MD/PhD and professor of neurology at Loma Linda University Health, who provided some insight on ALS, and what Randall may have faced in his battle with the illness.

"ALS is a progressive disorder that involves motor nerve cells," Dr. Rosenfeld explained. "Motor nerve cells in the body live in both the brain and the spinal cord and in the disease of ALS, both areas are affected in a progressive way."

According to Dr. Rosenfeld, one of the primary symptoms for most ALS patients presents as "some form of [physical] weakness." 

Over the weekend, Randall's death was confirmed in a statement released by his family.

"It is with great sadness that we share that on Aug. 5, Bryan Randall passed away peacefully after a three-year battle with ALS," read the statement. "Bryan chose early to keep his journey with ALS private and those of us who cared for him did our best to honor his request."

"We are immensely grateful to the tireless doctors who navigated the landscape of this illness with us and to the astounding nurses who became our roommates, often sacrificing their own families to be with ours," his family continued. "At this time we ask for privacy to grieve and to come to terms with the impossibility of saying goodbye to Bryan, His Loving Family."

Randall's family is asking that donations be made in his honor to ALS Research and Massachusetts General Hospital.

Bullock, 59, first met Randall, a photographer and model, when he photographed her son Louis' birthday in January 2015. Louis is now 13, and Bullock is also mom to Laila, 11. They went public with their romance later that year, but largely kept their relationship private. In 2017, the couple reportedly exchanged vows in an intimate, albeit not legally binding, ceremony in the Bahamas.

On Monday, Gesine Bullock-Prado, Bullock's sister, took to Instagram to pay tribute to the late photographer.

"I'm convinced that Bry has found the best fishing spot in heaven and is already casting his lure into rushing rivers teaming with salmon," Bullock-Prado wrote alongside a smiling photo of Randall. "ALS is a cruel disease but there is some comfort in knowing he had the best of caretakers in my amazing sister and the band of nurses she assembled who helped her look after him in their home."