Marc Spelmann is a magician who reached the Semi-Finals of Britain's Got Talent in Series 12. He received Ant & Dec's Golden Buzzer.
For his audition, Marc asked a task of four of the show's staff, helped by the other judges. He asked David to chose a colour of crayon, Alesha to choose a random animal from a pack of cards, Amanda to mix up a Rubik's cube randomly, and Simon to circle a word in a book. He then revealed that while knowing the choices beforehand would be considered 'magic', he discovered 'real magic' two years ago. He then played a video on the screen, explaining how his wife had been diagnosed with cancer, and that his daughter had to go through chemotherapy. He then revealed the correct answers to all four of the choices in the video, the word being said by his daughter two years ago. David, Alesha, Amanda, and Simon all gave him standing ovations. Moved by the performance, Ant & Dec pressed the Golden Buzzer for Marc, sending him straight to the Semi-Finals.
To begin his Semi-Finals performance he read a quote that just so happened to be on a screen behind him and stated the words 'through times of challenge we often learn life's most valuable lessons'. He then went on to state how strong his wife Tessa was through her cancer, through her words he made the decision to appear on BGT. He showed the judges a piece he created two years ago. He then gave Simon a gift of quote cards of quotes written by inspirational people, and asked him to pick one at random. He placed the card on Simon's hand and asked him not to tell him what it said. He gave both Amanda and Alesha a book each of inspirational quotes, and later gave David a copy of his own book, Mr. Stink. David later had to insert a bookmark somewhere in the middle of his own book. Amanda then looked at the page in her book and kept it upright. David repeated what he did previously, yet this time with Alesha turning to the bookmarked page in her book and keeping it held upright. Simon then read the quote he had a second time. Both Amanda and Alesha had their books on the page of an author that they were familiar with. Simon then read out the final word of his quote which was 'heart'. He then told Simon he had to finish a piece of art, yet his daughter Isabella drew a picture for Simon which was kept in an envelope nearby him. Simon then opened the envelope and showed everyone what the picture showed as it was a drawing of a large red heart. Marc then completed his art as he played a VT of his wife and daughter. Alesha disclosed the author she was thinking of which was 'Ghandi'. Via the VT Marc asked Isabella to tell him who he'd been painting for the last two years, as she went on to reply 'Ghandi'. Amanda then visualised her person as Marc went on to mix up the pieces of his painting of Ghandi and create a new painting of John Lennon. Hidden in the image of Ghandi was also the image of John Lennon. For his performance, Marc received a standing ovation from the audience, and the judges. Amanda commented that the 'magic [was] extraordinary'. Simon added that 'magic [felt] too small for [Marc's performance].' David then went on to add that he believed that Marc made 'magic beautiful.' Alesha agreed with David feeling 'almost entranced' watching Marc's performance. He reached the top three, but was beaten in the Semi-Final by Robert White. He then reached the judges' vote as he was sent home with two votes from David Walliams and Alesha Dixon. The vote was later taken back to the public vote due to opposition regarding Gruffydd Wyn receiving two votes from Simon Cowell and Amanda Holden. The public vote proceeded to send Marc home and Gruffydd through to the live final.
In 2019, Spelmann returned to the show under the mystery act of X. His act was described as a mystery person with a white mask. X qualified to the final and as part of the act in the final, Marc unveiled himself as X much to the surprise of everyone including the judges and Ant & Dec. When X revealed himself as Marc, he showed footage of his daughter Isabella in her cot. A book titled Hope by John Lennon was seen beside her, which may have been a reference to Spelmann's Series 12 Semi-Finals performance.
In early January 2020, he competed on America's Got Talent: The Champions' second series, reaching the semi-finals as one of the two winners of the super fan vote. He later competed in the semi-finals in early February 2020, but was eliminated due to lack of votes.
In winter 2020, he returned for the Britain's Got Talent Christmas Spectacular. He performed a routine based upon the decisions a human being makes upon a daily basis. He then had Ashley contribute by giving an item in a small Christmas box, David to sign the box, and Alesha to take a card with information. He then had Amanda dial a random number that she did not recognise and conduct the call on speakerphone. He then had Alesha show the info on the card to be the man on the phone 'Christian Nardy'. Nardy was then transitioned to a video call before Amanda was asked to pick a random word ('Beautiful'), before getting Nardy to repeat the word. He then headed upon the stage and retrieved his X attire and put it on. He then asked for a close-up on the big screen, asking the judges to watch closely and not remove their eyes from the screen. He then placed the box upon the table, which seemed to disappear. It then later reappeared with Christian on the video call, after X asked the camera to cut to the video call. He then had Christian open the box to reveal a bracelet of Ashley's. He then explained that several numbers flashed by upon the screen and Amanda could have picked any random combination. Marc however then revealed himself to be Nardy, before X removed his mask upon the stage and revealed himself to be Ant. After the performance Spelmann gifted Ant the X mask and gloves that he used.