- Real name: Unknown
- Alias: Blok
- Identity: Public
- Alignment: Good
- Gender: Male
- Occupation: Legionnaire
- Family: None
- Affiliation: Legion of Super-Heroes (Pre-Zero Hour); League of Super-Assassins
- First appearance: Superboy & the Legion of Super-Heroes #253 (Jul 1979)
- Alternate versions: Blok (Earth Zero); Blok (New 52)
Blok was a child on the planet Dryad when it was destroyed by a super-nova. The Dark Man convinced him and his fellow survivors (Lazon, Mist Master, Silver Slasher, Titania and Neutrax) that the Legion of Super-Heroes were responsible for the destruction of the planet (in fact, they had rescued the surviving inhabitants). Wanting revenge on the Legion for what they did, they went after the Legion as the League of Super-Assassins. When the truth was revealed, Blok left the group. However, the others stuck to the life of crime, joining up with Nemesis Kid's Legion of Super-Villains.
Now reformed, and appalled by what he and his former allies had done, Blok joined the Legion of Super-Heroes and became a valuable member. He formed particular friendships with Timber Wolf and the White Witch.