Coffey debuted as a wrestler for the independent promotion World Wide Wrestling League in 2010. Prior to his arrangement with WWE, he wrestled for various other promotions including Pro Wrestling Elite, Target Wrestling and the Scottish Wrestling Alliance, winning a number of titles.[7]
Coffey would regularly appear on the NXT UK brand, being accompanied by his brother Joe in a winning effort on the first ever televised match on NXT UK. They would both go on to form the stable Gallus alongside Wolfgang and feud with British Strong Style.[17]
On the 6 February 2019 episode of NXT UK, Coffey faced Walter in a losing effort in Walter's second match on NXT UK.[18] On the 4 October episode of NXT UK, Mark and Wolfgang defeated previous champions Mark Andrews and Flash Morgan Webster for the NXT UK Tag Team Championship, going on to hold it for 497 days.[19]
On the 14 July 2022 episode of NXT UK, Coffey defeated Noam Dar to become the new NXT UK Heritage Cup Champion.[20] He would soon lose it back to Dar on the 25 August episode of NXT UK.[21]
^"NXT UK results, Feb. 6, 2019: WALTER triumphs over Gallus' Mark Coffey". WWE. Retrieved 27 February 2020.
^Owen, Dei (4 October 2019). "NXT UK TV TAPING SPOILERS: NIGHT ONE IN BRENTWOOD". Wrestling Observer. Retrieved 4 October 2019.
^Guzzo, Gisberto (23 June 2022). "Spoiler: Title Changes Hands During 6/23 NXT UK Taping". Fightful. Retrieved 23 June 2022.
^Russell, Skylar (7 July 2022). "Spoiler: New NXT Heritage Cup Champion Crowned At 7/7 Tapings". Fightful. Retrieved 7 July 2022.
^Moore, John (16 August 2022). "8/16 NXT 2.0 Heatwave results: Moore's review of Bron Breakker vs. JD McDonagh for the NXT Title, Mandy Rose vs. Zoey Stark for the NXT Women's Title, Carmelo Hayes vs. Giovanni Vinci for the NXT North American Title, Tony D'Angelo vs Santos Escobar in a Street Fight, Cora Jade vs. Roxanne Perez". Pro Wrestling Dot Net. Retrieved 17 August 2022.
^Tessier, Colin (27 September 2022). "Gallus Arrested, Suspended For Attacking Referees And Security Guards On 9/27 WWE NXT". Fightful. Archived from the original on 28 September 2022. Retrieved 6 February 2023.
^Moore, John (4 February 2023). "NXT Vengeance Day results: Moore's live review of Bron Breakker vs. Grayson Waller in a cage match for the NXT Title, Roxanne Perez vs. Jacy Jayne vs. Gigi Dolin for the NXT Women's Title, New Day vs. Gallus vs. Pretty Deadly vs. Chase U for the NXT Tag Titles, Carmelo Hayes vs. Apollo Crews in a best of three falls match". Pro Wrestling Dot Net. Archived from the original on 5 February 2023. Retrieved 5 February 2023.
^Lambert, Jeremy (4 February 2023). "Gallus Win NXT Tag Team Championships At NXT Vengeance Day". Fightful. Archived from the original on 5 February 2023. Retrieved 5 February 2023.
^KEVIN, BERGE. "WWE NXT Great American Bash 2023 Results: Winners, Live Grades, Reaction, Highlights". Bleacher Report. Retrieved 31 July 2023.
^"ICW There's Something About Mary(hill) - Event @ Community Central Halls in Glasgow, Scotland, UK".
^"ICW Show Me Your Lizard - Event @ The Garage in Glasgow, Scotland, UK".
^Kreikenbohm, Philip (7 September 2013). "ICW Zero-G Championship". Cagematch - The Internet Wrestling Database. Retrieved 7 February 2023.
^"ICW Still Smoking - Event @ O2 ABC Glasgow in Glasgow, Scotland, UK".
^"ICW Spacebaws Episode IV: A New Hope - Event @ The Garage in Glasgow, Scotland, UK".
^Kreikenbohm, Philip (2 November 2014). "ICW Tag Team Championship". Cagematch - The Internet Wrestling Database. Retrieved 7 February 2023.
^"PWE: Pro Wrestling Elite". Archived from the original on 13 August 2017.
^"PWE: Pro Wrestling Elite". Archived from the original on 12 April 2018.
^"Pro Wrestling Illustrated (PWI) 500 for 2019 - The Internet Wrestling Database". www.profightdb.com.
^ ab"New Phenom: The ICW World Heavyweight Championship Reign of Drew Galloway". November 2022.
^"Polo Promotions issue a huge challenge for Saturday 17th June in Carlisle! Will THEY accept? Tickets just £10 at -... | By Target Wrestling | Facebook". www.facebook.com.