Laurel Kent is a thirtieth century direct descendant of Superman (first appearance: SB No. 217/2, Jun 1976: "Future Shock for Superboy").
She trains at the Legion Academy and applies for admittance to the Legion of Super-Heroes, but is turned down. Her only power is invulnerability, which is considered a duplicate of other members' powers. Due to her Kryptonian heritage, she is vulnerable to kryptonite.
When she first encounter's the teenaged Superboy, Laurel uses the alias "Elna" and makes reference to the fact that she strongly resembles the woman Superman is destined to marry (though no account is specific, "Elna" is an anagram of "Lane", a probable reference to Lois Lane).
At a later time at the Academy, Laurel is shot by a marksman using a kryptonite bullet. This is part of a larger scheme to seek revenge on all of the descendants of the Justice League of America, of which Superman was a founding member, by the League's immortal foe, Professor Ivo (Legion of Super-Heroes Annual No. 1, 1985: "Revenge Is a Dish Best Served Cold").