Thursday Rubinstein was once a brilliant scientist who was shunned by society for developing a new surgical procedure where a human's head is replaced with an organic computer made of malleable plastic. She was tired of the obsession with physical appearance, and instead opted for the simplicity of a ruby head. Her first goal was to perform the operation on herself, which succeeded. She then joined the Headmen, a group of cosmic geniuses, and battled the Defenders on several occasions. Ruby Thursday's greatest accomplishment was posing as a political party leader and gaining several supporters, mainly from women. She later allied herself with a creature named Dibbuk, and was responsible for Omega The Unknown's death.
At some point, Ruby became romantically involved with The Answer, though she refused his further advances. She was eventually assassinated by Bullseye, but her mind survived and resurfaced to battle She-Hulk. Afterwards, she rejoined the Headmen and battled the Heroes For Hire. At some point, she was imprisoned in The Raft, which Wolverine broke her out of in his plan against Romulus. Ruby was contacted by Romulus and her daughter's life was threatened, forcing her to give Romulus the information to Wolverine's plans. When confronted by Wolverine, Ruby attacked, defeating him by impaling him with the tentacles she had formed with her head. Soon, Cloak, Silver Samurai, Skaar, and Bruce Banner appeared, all battling Ruby Thursday. She held her own, but was eventually caught by Skaar and teleported back to The Raft by Cloak. It was later discovered The Answer is the one who had planned her escape. Recently in a Prison Riot she encountered and faced off against the Avengers Academy students. She managed to escape and her current whereabouts remain unknown.
Created by Steve Gerber, Sal Buscema and Jim Mooney. Ruby Thursday first appears in The Defenders #32.
Ruby Thursday is able to shape-shift her head into any shape she pleases, whether it be human in shape or an offensive weapon such as a sword. She had been seen to transform into many different appearances, such as a giant pair of lips, a shield, and a pair of wings. She can also sprout multiple appendages from her head, such as several arms or tentacles. Inside her head are several defensive weapons, such as stingers and explosive charges. Ruby Thursday is able to launch her head from her body at will and hover around, or simply explode her head and knocking everyone in her close vicinity unconscious. Due to her computer mind, Ruby is unable to be killed.
Thursday's "organic cranio-computer" can analyze her opponents' fighting styles, predict their future moves, and come up with counter-moves to neutralize them, although this capability is far less effective than, for instance, Midnighter's battle computer.
It has also been revealed that Ruby Thursday's current body is composed entirely of organic circuitry, and she is able to regenerate her body very quickly.