Character overview and history
Kurt Ryder was born a metamutant. The details of his parentage and early life are thus far unknown, up until his short stint as a circus acrobat. He was soon kicked out of the circus for looking and smelling too 'freakish'. In his first appearance in JLA: The New Blood #4, the other New Blood members; Apollo, Firebird, Mercury, Runaway, and Wraith, headed to New Jersey to investigate reports of a strange creature living in the wild. They discovered that the strange creature they were looking for was Kurt Ryder, now calling himself 'Jack', and taking the name of Nightcreeper as he joined the New Blood of the Judgment League Avengers.
Like the rest of the New Blood members, who were actually brought together secretly by Mister X, Nightcreeper joined the JLX as a founding member, generally used as comic relief, until a real story was brought up involving him and recent members Angelhawk and Kokoro. Nightcreeper and Angelhawk had both fallen in love with Kokoro, which was causing problems amongst the team. When the Armageddon Agenda arrived, Nightcreeper was among the metamutants who were imprisoned by the JLA. He also was one of the original members of the new JLX team, which was assembled by Wonder Woman when Fin Fang Flame attacked the JLA.