Matthew McCormick was born in 1222 in Salisbury, England. He first died in a jousting tournament in 1255 after being run through with a lance. After he revived as an Immortal, his first teacher was the Celtic warrior, Ceirdwyn.He later found new Immortal, Cory Raines, and took him as a student in turn.
In 1859, while living in the American south, he freed the newly Immortal Carl Robinson from enslavement, and took him as a student. Matthew taught him what he was and about the rules of the Game. He then advised him to go North, and let his anger for Seth Hobart, his former master, go. As Hobart was his father-in-law, he did not want the two to cross paths again.
Carl, still angry, however, left his teacher, went through Hobart's fields and killed Hobart and his son. Matthew, called Carl's revenge murder, however, and turned on Carl, swearing to exact justice.
In 1996, McCormick was working as an FBI agent as his cover, following up on reports of decapitations throughout the country. He picked up the investigation of the decapitation murder of a man called Myron Corman, a fellow Immortal, but most important was the name of the suspect: Carl Robinson.
Matthew still pursued Carl for killing his father-in-law, and sought to have Carl pay for the murder. Duncan MacLeod tried to convince McCormick to let go of his grudge. But Carl was arrested for the Corman killing. Later, however, Trey Franks confessed to killing Corman, freeing Robinson.Eventually, it came to confrontation and Robinson and McCormick drew their swords on each other. MacLeod tried to convince Matthew to drop the fight. At a disadvantage, Carl told Matthew to tell Trey Franks that he was not a nobody and that he was a good man. McCormick, also a good man, spared Carl, and let go of the long standing grudge. Then the three immortals conspired to 'kill' Carl and end the manhunt so Carl could move on to a new life.
McCormick carried a one handed English broadsword. He had been carrying the same weapon since the 13th century.
The character of Matthew McCormick, the immortal who worked as a federal agent tracking serial killers, was created specifically for actor Eric McCormack. The producers even considered giving him his own Highlander spin-off series, in which McCormick would travel the country where ever there was a series of beheadings and "investigate" the crimes while simultaneously dispensing immortal justice.