He was portrayed by Réal Andrews from 1996 to 1997 and again from 1998 until 2003.
He was also portrayed by Matthew St. Patrick in 1997.
On January 16, 2020, it was confirmed that Andrews would return to GH as Marcus Taggert beginning on Friday, January 17. He left again after being killed off on-screen on March 2.
Marcus Taggert grew up in Brooklyn where he got into trouble. He then met a kind police officer, Sonny Corinthos's stepfather Deke Woods, who took Marcus under his wing. Because of Deke's attention, Marcus turned his life around and became a policeman himself. He was devastated when his mentor was shot down in an alley and determined to get revenge on the alleged murderer, Sonny Corinthos.
In 1996, Marcus moved to Port Charles and got a job on the PCPD. He then took it upon himself to persecute and harass Sonny every chance he got. His vendetta with Sonny has gotten him in trouble on the job on more than one occasion. He even got involved romantically with Sonny's cast-off, Hannah Scott.
Before that, he had a soft spot for Sonny's first wife, Lily Rivera Corinthos, and her death via a bomb meant for Sonny just made Marcus hate Sonny more. Because of his fondness for Lily, Marcus allowed Juan Santiago, Lily's son by Miguel Morez that was given up for adoption, to become his ward.
Then, Marcus' sister Gia turned up in Port Charles. She had been attending Columbia University but decided that wasn't the life for her. She dropped out without her mother's knowledge and took a job as a nanny to a couple who lived in Port Charles.
When Marcus found Gia, Florence decided to move to Port Charles, too, so she could be near both of her children. Both Marcus and Florence Campbell rent apartments in the Brownstone owned by Bobbie Spencer. Marcus lives in the basement apartment where Felicia Jones used to live with her daughters. On May 8, 2003, Marcus was forced to move out of town by Scott Baldwin.
On January 17, 2020, Marcus returned to town and argued with Sonny over his return. Upon his arrival to the Port Charles Police Department, it's revealed that he was formerly partners with Commissioner Jordan Ashford and he was the mystery person she called and asked to come to town right away. On February 19, 2020, it was revealed that Marcus is the father of Trina Robinson.
On February 26, on the night of the school dance Trina is attending, Trina and Cameron Webber are being transported there by a rideshare driver who is really Walker, one of Cyrus Renault's henchmen, kidnapping them to get Marcus' attention after failing to kill him earlier. Trina and Cameron were being held hostage at gunpoint as Marcus arrives, but Cameron attacks one of the gunmen and flees with Trina as a nasty gun battle ensues. While Jason, Curtis, and Marcus exchange gunfire with Walker and his co-henchmen, one of them shoots Marcus in the stomach. Walker and his men were about to finish him off, but Jason and Curtis saved him and had him transported to the hospital. Meanwhile, Walker and one other henchman escaped since three of their colleagues were killed in battle by Jason and Marcus. Unfortunately, on March 2, Lucas reveals that Marcus has died from a blood clot in the brain due to his gunshot wound. Before he died, Marcus somewhat made peace with his life long enemy Sonny, and thanked him and Jason for saving his daughter.
Manufactured evidence with the help of Jordan Ashford, Bob Massicotte, and Mark Simon, and then framed Cyrus Renault for crimes which he was guilty of committing [pre-2010; revealed on Feb 6, 2020, details revealed on Feb 21, 2020]
Assaulted one of Cyrus' men who attacked him [Feb 26, 2020; self-defense]