Karl Munro is the former partner of Stella Price, the current landlady of the Rovers Return Inn. He got a job at Street Cars in June 2011. Later in the year, he had won himself £1,000 from Ciaran McCarthy after playing a card game with some of the lads in the back room of the Rovers. This was Ciaran's wedding money to marry Michelle Connor, but Karl went and spent it at Barlow's Bookies and didn't give Ciaran the money back.
Karl then got a gambling addiction, and went to spend the Street Cars fares at the Sunset Casino, but despite winning a lot of money, he had lost it all on one gamble. When Lloyd Mullaney questioned him about being absent all day, he made up the story that his car had broken down. Unbeknown to Karl, Lloyd had tried to kiss Stella after helping her in the Rovers, as she was supporting him after his break-up with Cheryl Gray.
In 2012 he began an affair with Sunita Alahan and began creeping about and almost got caught out by Dev and Kevin Webster. In July 2012 Karl continued his affair with Sunita for one night until Stella and her daughters Leanne and Eva came back to the Rovers to see Karl and Sunita. After that Stella broke up with Karl and banged on Sunita's door causing several of the neighbours to emerge. Stella then slapped former friend Sunita before calling her a slag just as Dev came out. Later that night Karl had to sleep in his cab after Stella threw him and his belongings out. However he was sacked by Lloyd the next morning.
Karl moved in with Sunita after Dev allowed her to live there. However Karl still missed Stella and began to regret his actions and disliked being with Sunita. Several times Karl began pleading with Stella to take him back, however she kept refusing. When her mother, Gloria turned up on the scene, Karl began asking her to talk to Stella, with no avail. When Karl came to realization that Sunita had deleted his text message on the night she wanted to have another relationship him, he angrily confronted her. He left, and returned to find Sunita changing the locks of the house. Karl later moved into a bedsit, and begged Steve to give him his job back, which Steve accepted after talking to Stella.
In 2013 Karl began to spiral out of control and it was clear he was still missing Stella. When Gloria's new fiancée Eric Babbage passed away, Karl started to show support by comforting Gloria and helped out behind the bar. However he was still in love with Stella and wasn't happy with her relationship with Jason Grimshaw and tried to convince her it wouldn't work as he was younger than her. When she got a cab back after a meeting from the Brewery, Karl picked her up and took her away for a talk. Karl broke down and a sympathetic Stella comforted him, but said he should try and move on and stop seeing her. The next day he returned, only for Gloria to blurt out about Karl locking Stella in the taxi, which promoted Lloyd and Steve to sack him a second time, and a smug Sunita looking on in glee. Karl later visited Sunita and threatened her that he wasn't going anywhere and he will be remaining. The next day, Karl stole Jason's van and torched it and gave the police Jason's description. But Jason had an alibi about being in the Rovers at the time. Stella, who didn't think Karl could be capable of doing such a thing, got him a job working for Owen Armstrong at his builders yard.