Magic Johnson is one of countless heartbroken fans mourning the death of "Cosby Show" alum Malcolm-Jamal Warner at the age of 54 ... with the Lakers legend sharing a touching tribute to the Emmy-nominated actor -- saying "he will truly be missed."
Johnson shared the tribute to X not long after TMZ broke the story that Warner died as a result of an accidental drowning while in Costa Rica with his daughter.
"[Cookie and I] were both super fans of the hit Cosby Show and continued to follow his career on shows like Malcolm and Eddie and The Resident," Johnson said.