Riddler is a thin man of medium height. He has brown eyes and brown hair in a flat-top, a spiky quiff with long sideburns and a rectangular head. He also has a gap between his two front teeth.
His Riddler costume is a colorful two-piece suit. He wears a dark green shirt and a lighter green jacket with a high collar; the shoulders are a darker green. A question mark is emblazoned on his left shoulder. He has a purple tie with a green question mark tie-pin in the middle. He also wears black pants with a green belt and question mark buckle, and triangular green glasses with a purple frame.
While imprisoned at Belle Reve Penitentiary, the Riddler tried to get on the good side of Icicle Sr., the head of the prisoners, but failed because everyone saw him as a joke. He again tried to approach the capo and the prisoners during lunch, but was once again rejected.
When a massive escape was attempted, the Riddler somehow managed to escape during the confusion when no one else could.
In a dimension without any children under the age of 18 (caused by a magic spell by Klarion and other sorcerers), Riddler infiltrated Gotham's STAR Labs. While Sportsmaster incited a riot outside to keep the police occupied, Riddler was able to sneak out with the last sample of Starro.
Later, Riddler and Sportsmaster presented the Starro tentacle to the Brain and other members of the Light.