Before the hit Hollywood epic known as "Gladiator", Joaquin Pheonix started his acting career in television guest roles, most notably, on Superboy: The TV Series (season 1). At that time, Joaquin was known as Leaf Pheonix because his parents named their children after "nature" names, like his brother was named River Pheonix. Leaf Pheonix eventually changed his stage name to Joaquin when he got older.
In the episode titled "Little Hercules" in Superboy season one, Joaquin plays an awkard character, a small freshman who is in love with an attractive girl at his High School. "Billy Hercules" is a computer genius and teams up with Superboy when he accidently starts a countdown for a nuclear holocaust on his home computer. He and Superboy have to stop this mistake from destroying the entire world from nuclear weapons.
This episode alone proves the genuis being Ilya Salkind and his early casting instincts. Though Joaquin has disappeared from acting, he can still be found on the season one DVD set distributed by Warner Brothers. So be sure to purchase Superboy, season one on DVD (now available on amazon.com).
Joaquin Pheonix with Ilya Salkind (1988).
I actually found a clip of the openning dream sequence on youtube (click here). Joaquin "Billy Hercules" uses heat vision like Superboy.