It's a rarity to see superheroes that are moms or dads, but it does happen from time to time. In the DC Universe, Superman and Lois Lane have Jon Kent aka Superboy, Batman has Damian Wayne aka Robin, and Flash has not only children, but grandchildren with the Tornado Twins, Impulse, and XS. In Marvel, Mister Fantastic and Invisible Woman have two children, Franklin and Valeria, while Cyclops and Jean Grey have two kids of their own, Rachel Summers and Cable. These aren't all the examples of superhero parentage, but it's a fair amount of them.
But as rare as it is for superheroes to have kids, it's even rarer for supervillains to have them. The life of a super-criminal doesn't lend itself to rearing children, mostly because the bad guys tend to spend most of their time in Arkham Asylum, Blackgate Prison, or the Raft when they aren't trying to pull off their schemes. Still some villains have found time to have kids, like Batman's old rogue Riddler and his daughter Enigma.
Enigma first showed up in 2006's Teen Titans vol 3 #38 by Geoff Johns, Carlos Ferreira, Art Thibert and Drew Geraci, where she joined the superhero team alongside Duela Dent, the daughter of Earth-3's Jokester and Three-Face. At the time, Enigma claimed that she was trying to get the attention of her dad, the world-famous Batman rogue Riddler, while her pal Duela Dent was also looking to grab her father's eye. The duo's time with the Teen Titans was short, with both of them leaving the team to join Deathstoke's Titan's East, a team of teen villains that included the Bizarro Superboy Match and the evil clone of Impulse called Inertia. When the Titans East faced off against the Teen Titans, it was Enigma and Duela Dent's job to take out Raven via psychological torture in a literal hall of mirrors.
Raven proved to be mentally stronger than Deathstroke and his team had anticipated, and she was able to convince Duela Dent to turn on her friend and return to the ranks of the Teen Titans. Duela knocked out her friend and released Raven, ensuring that the Teen Titans would come together to fight the Titans East. Making matters worse for Enigma and her team, the Titans showed up to help their teen counterparts battle Deathstroke and his crew. Enigma had joined the Titans East hoping to get her father's attention, and apparently it worked.
Enigma was next seen working with her father the Riddler as his obeying sidekick as they battled against Batman and Catgirl. Much like her time with Titans East, things don't go the way Enigma had hoped and she ended up back in jail. At some point, Enigma broke herself out and rejoined her father on his criminal capers. By this time, Riddler had become a far darker figure, and Enigma followed suit. While helping her father break into a mansion owned by the Falcone crime family, Enigma had no issue with killing people. After the massacre at the Falcone home and believing that the break-in was a waste of time and effort, Enigma finally spoke up against her father. No longer seeing a reason to keep her around, Riddler killed his daughter.
Like many low-tier characters in comics, Enigma's death went virtually unnoticed by the other heroes and villains in the DC Universe. Just two months after Enigma's death, Flashpoint would reboot the DC Universe and New 52 would begin. Like many others, it seems that Enigma's very existence was erased from continuity.