Supergirl Season 1 Episode 17: Manhunter
Jim Harper AKA the Guardian was introduced by Jack Kirby and Joe Simon in Star-Spangled Comics #7 (April 1942). Kirby and Simon are also the creators of Captain America, Manhunter (Paul Kirk), Captain 3-D, and the Fighting American. Harper was a policeman that became a vigilante. He had a squad of newsboys who helped him on his adventures who were called the Newsboy Legion. He patrolled the streets of the Suicide Slum in Metropolis. The Newsboy Legion grew up to be scientists at Project Cadmus and cloned Jim. They put aging Jim’s mind into the younger cloned body. Originally the clone was called the Golden Guardian, after the Crisis on Infinite Earths he was simply the Guardian. Post Infinite Crisis he became the leader of the Metropolis Science Police.
Project Cadmus was created by Jack Kirby and introduced in Superman’s Pal Jimmy Olsen #133 (October 1970). Originally it was called the DNA Project. It was re-introduced in 1988. It was responsible for creating Superboy (Kon-El/Conner Kent a clone of Superman and Luthor), the Guardian clone, Dubbilex (the DNAlien), and Auron. Some of its directors’ methods were not ethical. That seems to be the situation on the show as well.
Gotham Season 2 Episode 15: Mad Grey Dawn
Riddler AKA Edward Nigma was introduced by Bill Finger and Dick Sprang in Detective Comics #140 (Oct. 1948). In the comics he is a master at puzzles. He decided to antagonize Batman, because he viewed him as his only true worthy adversary. He saw the World’s Greatest Detective as the only one worthy to challenge him.
Ivy is based on Poison Ivy the classic Batman villainess. Pamela Lillian Isley AKA Poison Ivy was created by Robert Kanigher and Sheldon Moldoff. She first appeared in Batman #181 (June 1966). In her first appearance she was Dr. Lillian Rose. Due to an accident she became immune to all viruses and toxins. After the Crisis on Infinite Earths, she becomes Pamela Lillian Isley, a brilliant bio-chemistry student. She was seduced by a professor and he used her as a lab rat by poisoning her with various toxins. This transformed her into a plant controlling metahuman with immunity to all viruses and toxins. She subsequently starts her life of crime afterwards. Her origin is slightly different post New 52. She was always experimenting on people and manipulating them as well. She experimented on herself that left her with super immunity. This experiment also gave her the ability to control plants. Over the years she has been a member of several supervillainous groups, but she also has been a member of the Suicide Squad and the Birds of Prey.
The Flash Season 2 Episode 16: Trajectory
Eliza Harmon AKA Trajectory was created by Geoff Johns, Grant Morrison, Greg Rucka, and Mark Waid in 52 #17 (August, 2006). She was a member of Lex Luthor’s Infinity Inc. She was part of Project Everyman where Luthor gave superpowers to a group of people. She needed to take drug called Sharp to slow down to normal speed. She was stripped of her powers by Luthor in a battle with Blockbuster, which led to her death. When Eliza remarks about Caitlin being all Law & Order that is a reference to Jesse L. Martin’s (Joe West) former show.
Arrow Season 4 Episode 16: Broken Hearts
Cupid Aka Carrie Cutter debuted in Green Arrow/Black Canary #15 (February 2009) by Andrew Kreisberg and David Baron. She was a former special ops soldier that found out her believed to be dead husband was alive. She tracked him to Star City and killed him. In Star City she became obsessed with the Green Arrow. In her obsession she killed a number of Green Arrow’s adversaries. This was all done to impress him.