Superboy [Kal-El; Clark Kent; also as infant (flashback); also as Superman (cameo)]; Jimmy Olsen (as toddler and as adult, cameo); Professor Mark Olsen (Jimmy's father) [also disguised as Superman]; Mrs. Olsen (Jimmy's mother); Vedders; Sir Roland; other descendants of knights from the Crusades; Jonathan Kent (flashback); Martha Kent (flashback)
Superboy [Kal-El/Clark Kent]; Jimmy Olsen; Lana Lang; Jonathan Kent; Martha Kent; Clark and Lana's classmates; the people of Smallville; adult Clark Kent
Superboy [Kal-El/Clark Kent]; Jonathan Kent; Perry White; Lois Lane; the editor of the Metropolis Times; a spelunker; Lana Lang; two members of the Bullet Gang; Daily Planet staffers; the people of Metropolis
Superboy [Kal-El/Clark Kent]; Robin [Dick Grayson]; Pete Groff; Batman [Bruce Wayne] (cameo); Superman; a surgeon; Professor Carter Nichols; Professor Wilcox; Professor Higgins; Professor Wolfe; Jonathan Kent; Martha Kent; Lex Luthor; the Bandit Gang
Superboy [Kal-El/Clark Kent; also costumed as Wyatt Earp for a school history pageant]; Oliver Queen (the future Green Arrow) [also costumed as Robin Hood for the pageant]; Lana Lang; Green Arrow [Oliver Queen] (on time-screen); Oliver Queen's butler (on time-screen); a history teacher at Smallville High School; a man dressed as Jesse James; a boy dressed as John L. Sullivan; a boy dressed as King Arthur; a man dressed as Sir Modred; Tom Hawkes [boy dressed as Harry Houdini]; Jim Brand of the Brand B Ranch; Fred Winters [boy dressed as Benjamin Franklin]; man dressed as the Sheriff of Nottingham; Will Bronson [boy dressed as Daniel Boone]; man dressed as a Cherokee chief; police officer
Superboy [Kal-El/Clark Kent]; Supergirl [Kara Zor-El/Linda Lee]; Superman; Tommy Dale and his friends; Zor-El (flashback); Alura (flashback); the people of Argo City (flashback); two alien mermen; Martha Kent
Superboy [Kal-El; Clark Kent]; Lori Lemaris; Jim Saunders (owner of the Seaside Aquarium); Saunders' landlord; Lana Lang; Professor Lewis Lang (Lana's father); Britt Lemaris (Lori's father); Omra Lemaris (Lori's mother); two of Lori's friends; people of Poseidonis (home of Aquaman); young Arthur Curry (the future Aquaman) (cameo); Tom Curry (Arthur's father) (cameo); Atlanna (Arthur's mother) (cameo); Morgol (Lori's sea-creature pet); people of Tritonis (Lori's home city); a giant sea crab; Jonathan Kent; Martha Kent
Superboy [Kal-El/Clark Kent]; teenaged Jor-El (briefly ages to adulthood); Jonathan Kent; Martha Kent; Krypto the Superdog; Lex Luthor; a sea serpent; Blak-Du (Phantom Zone criminal and former college roommate of Jor-El); two unnamed Phantom Zone criminals
Superboy [Kal-El/Clark Kent]; Aquaboy [Arthur Curry] (the teenaged future Aquaman); Mac and Jim (two fishermen); three workers at Industrial Detergents, Inc.; Aquaboy's porpoise friends (one of whom dies from drowning in crude oil in flashback); the captain and crew of a Trans-East oil tanker; two top executives of Trans-East Oil Co.; Marita (Aquaboy's girlfriend)
Superboy [Kal-El/Clark Kent]; the Executioner [Bruce Wayne] (the teenaged future Batman); several DC Comics editors on Earth-Prime; Jonathan Kent; Martha Kent; a burglar; Thomas Wayne (flashback); Martha Wayne (flashback); Joe Chill (flashback); Batman [Bruce Wayne] (on time-screen); Superman (on time-screen); two criminals (on time-screen); two arsonists; several Gotham City firefighters; a police officer; a crowd on a Gotham pier; Otis Higbee (reporter for the Gotham Gazette); several supposed victims of the (non-existent) "Zodiac Killer"; Bruce Wayne's collection of bats; judges, contestants and spectators of a fishing contest; editor of the Gotham Gazette (flashback)
Superboy [Kal-El/Clark Kent]; Hal Jordan (teenaged future Green Lantern); Lana Lang; students of Smallville High School; two escaped circus tigers; two middle-aged women; Martha Kent; Jonathan Kent; the captain, co-pilot (named Hansen), a flight attendant and several first-class passengers on Flight 609 from Metropolis to Coast City; Martha's sister Mary and her husband, Fred; Jack Jordan (Hal's brother); Jim Jordan (Hal's other brother); Officer Rowe of Smallville PD; several mobsters in Smallville; Fred's niece, Esther; teenagers and other people on a California beach; a family in a sinking boat, rescued by Superboy; several sharks; guests at Mary and Fred's silver anniversary party; several smugglers; Green Lantern [Hal Jordan] (cameo)