Name: [Unrevealed] of Earth (75th century)
First appearance & joined: Superboy v.1 #204 (October 1974)
Anti-Lad was "The Legionnaire Nobody Remembered"… and that's fine with him. This bald-headed young man was from the 75th century, and reviewed the Legion's history. He was most concerned with the day that the legendary hero, Superboy, joined their ranks. (Adventure #247) But when he viewed the day with his time-scanner, he found that the Legion had not admitted him to the group after all!
Instead of joining the Legion, Superboy was rejected and he pleaded with them to give him another chance, to no avail.
With the help of his father, Anti-Lad he deduced that something had gone wrong with the time stream. The lad took drastic measures, stealing his father's "timesmitter" and going back to that day in the 30th century. He appeared after Superman had been rejected, just as a grim Cosmic Boy announced that he was opening the floor to other nominations. On cue, a tall young man materialized on the round table in a burst of flame and identified himself Anti-Lad. He explained his visor: "On the faraway planet I come from, our sun is 1,000 times brighter than yours. The visor amplifies Earth-light so I can see."
In a series of trials, Anti-Lad demonstrated how he came by his name, reflecting the powers of each Legionnaire back at them—changing others' strengths into weaknesses and turning their own powers against them.
Brainiac 5 was suspicious of him, though, and revealed that Anti-Lad was using technology to emulate super-powers. Anti-Lad convinced the Legionnaires that it was he who had handicapped Superman with kryptonite during his Legion tryout. Thus, they gave Superman another chance.
When Anti-Lad returned to his future, he erased the Legionnaires' memories of his appearance, but left a strange image of himself on their holo-files. (Superboy #204)
Years later, the Legion would unearth a photo of themselves and a stranger in their archives and wonder "Who was Anti-Lad?"