Nick Hogan Calls Dad Hulk 'Hero' and 'Best Friend' in Touching Tribute

Hulk Hogan's son has finally addressed his dad's passing ... breaking his silence with a heartfelt post to Instagram late Saturday night.

Nick Hogan dropped a ton of photos from over the years with his dad ... starting from when he was just a kid and his dad ruled the squared-circle and continuing to their time advertising Hulk's beer brand "Real American" together.

Nick -- who turned 35 Sunday -- starts out his caption by thanking everyone for their well-wishes during this difficult time ... and for telling so many wonderful stories about his dad in the days since his shocking death.

Hogan then goes into what his dad meant to him ... calling Hulk his "hero" and the "greatest dad in the world" -- who was also a best friend and mentor to him.

Nick adds, "I thanked him for everything he has ever done for me and told him how much I loved him and hugged him every chance I got. I spent a lot of time with him the past few years after moving back to Florida to be closer to him and I am so grateful for those memories. They are the best moments in my life."

NH finishes off the statement by saying he'd do anything to get his dad back ... but, he's grateful to know he's got a guardian angel like Hulk looking out for him now.

We broke the story ... medics were called to Hulk's home in Clearwater, Florida Thursday -- and, video captured them frantically performing chest compressions as they transported him to the ambulance. Hogan was pronounced dead at the hospital.