Early into his superhero career, Matt Murdock sporadically assumed the identity of a fictional twin brother of his to help conceal his alter-ego of Daredevil. Matt pretended that this twin brother, named Mike Murdock, was Daredevil's secret identity. Matt eventually got rid of Mike Murdock by setting up his death (and saying that a new Daredevil had been trained).^[4] Over the years, Matt would sometimes still use the identity of 'Mike Murdock' to go undercover.^[5]

After Daredevil enlisted the help of the Inhuman named Reader to form a group to take down Mayor Wilson Fisk, Reader accidentally used his ability to physically manifest anything he read while researching on Mike Murdock, which resulted in his manifestation as a real person who genuinely believed himself to be Matt Murdock's twin brother, and possessed both the abilities and brash personality he was supposed to have. Reader called this kind of creation a "fragment."^[5] As Daredevil, Matt stumbled into Mike in the Bar with No Name,^[6] and knocked him down to investigate what was going on. When Reader figured out Mike Murdock's existence was his fault, he tried to use his powers to "unwrite" him. Mike escaped, taking Reader's dog Forey hostage. Mike managed to continue evading Daredevil,^[5] and took Foggy Nelson hostage to arrange a meeting with Matt.

When they met up in High Line Park, Matt started to doubt his decision to erase Mike, valuing his brother's existence even though it was an accident. When Reader arrived to erase Mike, Matt stopped him and let Mike go. Desperate for help, Mike sought Mayor Fisk, and offered to do any kind of job in exchange for protection. Fisk accepted Mike's proposition, and later sent The Hood to recruit him.^[7]

After doing a successful heist with The Hood, Mike stole a Norn Stone from his vault and hired Black Cat to steal an English translation of Asgardian spells in order to become a full human. The ritual worked and rewrote history, with Mike becoming Matt's actual twin brother. In this new rewritten past, Jack Murdock raised his sons alone after their mother Maggie left due to her mental health issues. While growing up, Mike would defend his brother from bullies who mocked him, despite Jack not approving of this. Mike would also form a friendship with his neighbor, Butch. Jack urged his sons to study hard for them to become doctors or lawyers, but Mike dropped out of summer school leaving Matt to go instead. However, this would leave Matt to get involved in an accident that left him blind. Mike felt guilty for the accident and stayed with Matt at the hospital while he recovered. One night he saw a nun praying for Matt, and Mike figured out she was their thought deceased mother.

Mike began descending into criminal life, at first scamming people with his partner Butch, before eventually being kidnapped by a group of gangsters, leaving his father to help him escape. After realizing that Mike wouldn't really make something of himself like he originally had hoped for, Jack decided to train Mike in combat. However, Mike became angry at him for lying to them about his dirty fights and about his mother and told him that he wasn't like his brother Matt. After Jack made a deal with the Fixer, Mike feeling confident that his father would win, met with Fixer and Owl and bet a huge amount of money for his father. After he and his brother Matt saw their father won the fight, Jack was murdered since he was supposed to lose. This left Mike to feel guilty again for potentially having a role in his father's death.

Years went on, and, after Daredevil turned himself in for murder, Mike met with his brother, since he was now hunted by the Hood for stealing from him, but the conversation soon went sour and the superhero left. Mike then met up with his friend Butch and the two celebrated in honor of their fathers, Jack Murdock and Wilson Fisk.^[1] During Daredevil's trial (and subsequent incarceration), Mike impersonated his brother as a favor to Foggy.^[8] However, this turned out to be his undoing, when he was visited by Wilson Fisk, who mistook him for Matt and beat him to death with his bare hands.^[9]

Skilled Combatant: Mike was taught for a time how to fight by his father.^[1]

• Mike's best friend was Butch Pharris.^[10]