|Kid Quantum I|
|Alter ego||James Cullen|
|Abilities||Ability to freeze time in limited areas, dependent on technological amplification|
|Kid Quantum II|
|Alter ego||Jazmin Cullen|
|Team affiliations||Legion of Super-Heroes|
|Abilities||Ability to speed and slow time|
Time travel (dependent on external conditions)
The first, James Cullen, used a so-called "stasis belt" to augment his power to freeze time within a limited area to useful levels. He became a member of the Legion of Super Heroes and became its first member to die between his overconfidence and a belt malfunction.
The second Kid Quantum was Cullen's sister Jazmin. After her brother's death, she underwent surgery to augment her power to a level where she would not require the belt. Despite initial hostility to the Legion when she first joined, she eventually grew within the role to the point where she was elected leader of the team, thanks in large part to Cosmic Boy's recommendation of her. She later entered into a relationship with him.