Bob Cole – Voice of the Republic (appears in 68 episodes from season 1-5)
Jake Doyle – Jake is a 30-year-old man living with his father Malachy because his ex-wife Nikki kicked him out. He works as a private investigator with his father, Mal and his father’s wife, Rose. He is over-protective of his 16 year old niece, Tinny. He is the youngest child of Mal Doyle and his late wife Emily Ann, and their second son. He also drives a 1968 Pontiac GTO.
Leslie Bennett – Leslie is a Sergeant in the Royal Newfoundland Constabulary who is friends/lovers with Jake and gives him information to help with his cases. Leslie is Jake's source of distraction from his cases and personal life. She is a sharp shooter, very intelligent and a great match for Jake. She and Jake have real feelings for each other, but seem to show them the wrong way, making their relationship complicated but very interesting.
Malachy Doyle – Malachy, known as Mal or Skipper and Poppy, is a private investigator with his son, Jake in their business "Doyle and Doyle." He is 56 and has 3 “grown” children, Christian, Kathleen and Jake, and one granddaughter Tinny who is living with him while her mother (Kathleen Doyle) is away working in Alberta. His wife Rose lives with him, his granddaughter, and his youngest son Jake. He pokes fun at Jake's somewhat 'unsuccessful' relationships with women.
Rose Miller – Rose is Mal's wife. She works as the office manager/secretary for Doyle and Doyle. She seems to have a love/hate relationship with her husband’s granddaughter Tinny and his son Jake. Rose's criminal ex-husband, Martin Poole, keeps turning up.
Nikki Renholds – Nikki is Jake's ex-wife. Nikki is a physician at a St. John's hospital. Nikki helped out with different cases in the first few episodes.
Katrina 'Tinny' Doyle – Tinny is the daughter of Kathleen Doyle. She lives with her grandfather, Mal or Poppy as she calls him, Uncle Jake and grandfather’s wife, Rose. She is 16 and can’t stand her grandfather and uncle's over-protective nature. She has a love/hate relationship with her grandfather's girlfriend, Rose and one of the employees and main characters, Des Courtney.
Des Courtney – Des is the fashion-challenged and delinquent graffiti artist who tags the town and Jake’s beloved Pontiac GTO until Jake brings him to heel – and into the employ of Doyle and Doyle Investigations. He is 19 and has a crush on Tinny, leading Jake to dislike him. His real name is Desmond Redmond, and he is the son of the infamous, yet equally as dopey, Jody Redmond. Not wanting to be associated with his father, Des conceals his identity.
Walter McLean – Walter has been Jake's best friend since kindergarten and his wing-man that used to be right behind Jake in a fight. Walter was Jake's lawyer in his divorce from his wife Nikki. Walter appears only sporadically. In season 3 he becomes romantically involved with Tinny's mother Kathleen.
Allison Jenkins (season 2, guest starring in season 4) – Allison is the crown attorney and has all the things that turn Jake's head. What was once strictly professional has since turned into a romantic relationship.
The show is filmed in St. John's, Newfoundland. The show's star, Allan Hawco, is also executive producer/showrunner/co-creator and head writer of the show.
Other producers include John Vatcher (exec producer), Rob Blackie, Perry Chafe (co-creator and writer) and Michael Levine.
In 2013, Republic of Doyle aired a fictional crossover with another CBC Television crime drama, Murdoch Mysteries. With the two shows set over 100 years apart, Hawco appeared on the November 25, 2013 episode of Murdoch Mysteries as Jacob Doyle, a 19th-century ancestor of Jake Doyle, while Yannick Bisson appeared on a January 2014 episode of Republic of Doyle as Bill Murdoch, a 21st-century descendant of his regular character William Murdoch.