Supergirl series guest stars: 

Jeremiah Danvers, Kara's Earth adopted father -played by Dean Cain - 90s TV Superman

Eliza Danvers, Kara's adopted Earth mother - played by Helen Slater - 80s movie Supergirl 

Alura Zor-El, Krypton birth mother of Kara - played by Erica Durance - Lois in Smallville 

Indigo, Braniac 8 -played by Laura Vandervoort - Kara/Supergirl in Smallville 

Olivia Marsdin, President - played by Lynda Carter - 70s TV Wonder Woman

 Rhea, Queen of Daxan - played by Teri Hatcher - 90s TV Lois

 Lar Gand, King of Daxam - played by Kevin Sorbo - TV Hercules - he didn't act as a character in a Superman show or film - but he was Hercules which is worth a mention 

Lex Luthor - played by Jon Cryer - who was the nephew of Lex in Superman 4 

It is a real pity that Tom Welling didn't get the chance to appear as a character - he did get to appear as Cain in Lucifer .