"See ya, pal. I'm going to miss you," Brolin wrote alongside a photo of the two. "You were a smart, challenging, brave, uber-creative firecracker. There's not a lot left of those. I hope to see you up there in the heavens when I eventually get there.

Val Kilmer has sadly died at the age of 65 after suffering from a bout of pneumonia, with Hollywood stars such as Josh Brolin paying tribute to the Top Gun actor