|Portrayed by||George Sampson|
|First Appearance||Series 6 Ep 11|
|Last Appearance||Series 8 Ep 30|
Kyle Stack is a former pupil of Waterloo Road. He was friends with Denzil Kelly, Harry Fisher, Harley Taylor, Sambuca Kelly and Tariq Siddiqui and previously with Finn Sharkey, Amy Porter, Lauren Andrews and Josh Stevenson. Christopher Mead and Tom Clarkson always have an eye on him. He was expelled from Waterloo Road when he slapped Nikki Boston. Some days later, he tried to kill Finn Sharkey but intentionally injured Josh Stevenson. He was sentenced to prison for aproxmaitely 2 years. When he was freed, he returned to Waterloo Road but Josh's father and English teacher Tom Clarkson didn't want him in the school. After a talk with other teachers, Tom accepted him back in class, and admitted that Kyle have changed. Kyle realized that some people were always going to see him as an attempted murderer and convict and subsquently tried to kill himself by jumping off the roof of the school. He was pulled from the ledge at the last minute by Tom but events following this led to Tom falling off the roof in place of Kyle. Tom had just enough breath left in him after falling the substantial height of the roof to whisper, "It's not Kyle's fault," then die in front of the crowd who had gathered. After this accident, Kyle decided to leave Waterloo Road because he thought he was responsible for Tom's death.
Kyle is every teacher’s worst nightmare: mouthy, disrespectful and disruptive. He honestly doesn’t care which makes disciplining him a nightmare and isn’t scared of expulsion as he doesn’t want to be there anyway. Kyle doesn’t care about the police because they’re round his dad’s house all the time. There really isn’t much to recommend about this surly, aggressive child – he has none of the cheeky intelligence of Finn Sharkey or the spark and potential of Ronan Burley , and if the teachers were being honest they’d admit Kyle’s a bit of a lost cause.
In the eleventh episode of the sixth series Kyle hits Waterloo Road with a bang. He sets his pet rottweiler loose and it ends up attacking the Headteacher's daughter Bex Fisher . When Kyle's dog is taken away to get put down, Kyle unleashes a sensitive side to his personality.
In the penultimate episode of series six, Kyle auditions for the school pantomime "Cinderfella" and impresses the whole audience (besides Finn) and he is given the main part. This increasingly annoys Finn and he purposly winds Kyle up so that he will lose his temper and lash out on Finn. Kyle takes his expulsion from the play badly and seeks revenge on Finn. By the end of the episode they become friends. However this does not last long.
In series 7 Kyle joins a gang known as the DSC. He, Tariq Siddiqui and Mason Price start tagging parts of the school and sabotaging classrooms. When Mason is arrested for knife crime, Kyle reveals to Tariq he was only "all mouth" and wasn't really friends with Mason. Tariq and Kyle become friends and Kyle brings Tariq into the DSC. They get into a number of fights with rival gang leader Eugene.
Following his expulsion Kyle begins to lose himself. He begins selling cannabis and lives in a broken down car in the forest. When he finds out Finn tried to torch Tariq's sister Naseem's shed, he is eager to help him get revenge. This involves smuggling a crossbow into the school. When Tariq hides the crossbow constantly and claims it is missing, Kyle breaks into the school during the prom and takes it from his hiding place. When Kyle is about to shoot Finn, Tom clarkson pushes him away and the bolt grazes his arm. Kyle is arrested for serious assult and for illegally being in the possession of a weapon. He is later sent to prison for Actual Bodily Harm.Kyle returns in the final episode of Series 8 from serving his time in prision. He appears to have changed and is now taking an actual interest in his studies, which leaders the new deputy head and the headmisteress to allow him to stay for a trail run. It is revealed that while in prision he assaulted an inmate for "no reason", although Kyle later states to duty head Simon Lowsley that the inmate had in-fact, insulted his mother. Throughout this episode Tom Clarkson and the deputy head attempt to help Kyle, and work out why he's come back to the school. He later shows violence against Barry Barry (again with comments about his Mother), . He is restrained and runs away, although at the end of the episode he is seen to about to commit sucicide. Tom steps up to help him, and Kyle makes the move to step down from the roof, but Tom falls off the roof and dies. He was last seen being taken off the the roof by Simon Lowsley and it's unknown what happened to Kyle.