Jerro the Mer-Boy
When Supergirl is summoned to Atlantis by Lori Lemaris in October 1960, she meets and has a romance with Jerro. Because Atlanteans are telepathic, Supergirl is soon embarrassed when her crush on Jerro becomes known. Banned from marriage by Atlantean tradition, they soon part but continue to pine for each other (Act No. 269/2, Oct 1960: "Supergirl's First Romance").
Supergirl meets Jerro again on her 16th birthday when she returns to Atlantis for a rescue operation (Act No. 270/2, Nov 1960: "Supergirl's Busiest Day").
In January 1962, Jerro proposes marriage to Supergirl when she is temporarily transformed into a super-mermaid by Red Kryptonite and rescues the mermaid Lenora Lemaris, who also loves Jerro (Act No. 284/2, Jan 1962: "The Strange Bodies of Supergirl")
When Supergirl is finally revealed to the world by Superman, she is congratulated by the people of Atlantis and Jerro telepathically remarks, "Supergirl will be too busy saving worlds to think of me". However, Supergirl's room in the Fortress of Solitude is revealed to have a picture of Jerro on the wall (Act No. 285/1, Feb 1962: "The World's Greatest Heroine").
Supergirl encounters Jerro in her search for the rare isotope Element Z, needed to save the life of Lex Luthor, in the process discovering the shrine of Garr Rindaz, an Atlantean hero (Act No. 286/2, Mar 1962: "The Death of Luthor!").
Jerro next appears when he and Dick Malverne temporarily acquire super-powers of their own (Act No. 290/2, Jul 1962: "Supergirl's Super Boy-Friends").
When Vostar, an evil Atlantean scientist, plots revenge against Lori Lemaris and Jerro, Supergirl must battle a berserk Comet the Super-Horse to save them (Act No. 302/2, Jul 1963: "The Day Super-Horse Went Wild").
Jerro and Supergirl meet again when they give Biff Rigger a hero's burial in Atlantis (Act No. 303/2, Aug 1963: "Supergirl's Big Brother").
Jerro appears again in June 1965 (Act No. 325/2, Jun 1965: "The Ugly Duckling Teacher of Stanhope College").