Killian Dain

Damian Mackle (born 20 February 1985) is a Northern Irish professional wrestler.

He is known for his time in WWE, where he performed under the ring name Killian Dain.

Since his departure from WWE, he has reverted back to his ring name on the independent circuit, Big Damo.

The ring name Big Damo is derived from his first ring name, Damian O'Connor.

Prior to joining WWE, he won the ICW World Heavyweight Championship while wrestling for Insane Championship Wrestling.

He also wrestled for numerous promotions on the British independent circuit, around Europe, and in the USA including All Elite Wrestling, Progress Wrestling, Revolution Pro Wrestling, Westside Xtreme Wrestling, Absolute Intense Wrestling, Beyond Wrestling, Premier British Wrestling, Scottish Wrestling Alliance, What Culture Pro Wrestling and IPW:UK.

While they never officially split up, they would both focus on singles competition around 2009.

This proved to be fruitful for both and O'Connor started touring his native Ireland, the United Kingdom, mainland Europe and the United States.

O'Connor would win the Heavyweight Titles in SWE, W3L, XWA, Pride as well as the Laird of the Ring Title in SWA.

In 2009, O'Connor took over the SWA training school named the "Source Wrestling School".

O'Connor has trained numerous wrestlers, including Joe Coffey, Joe Hendry and Nikki Cross.

O'Connor wrestled sporadically for ICW between 2009 and 2012 under various gimmicks, but his return in November 2013 saw him debut as Big Damo.

In December 2014, Damo unsuccessfully challenged Drew Galloway for the EVOLVE Championship in Inverness, Scotland.

In 2014, Damo debuted in Revolution Pro Wrestling.

In 2015, he wrestled NJPW greats Tomohiro Ishii, Hiroshi Tanahashi Shinsuke Nakamura, as well as Tommaso Ciampa.

In October 2015, Damo debuted for Global Force Wrestling (GFW) on their UK Invasion tour, losing to Bram.

On 19 October 2016, WWE announced that Mackle had signed a developmental contract with the company and had arrived at the WWE Performance Center in Orlando, Florida.

He began to work on the NXT brand as part of the stable Sanity, along with Nikki Cross, Eric Young and Alexander Wolfe.

After a long feud with Drew Galloway, Damo defeated Chris Renfrew for the ICW World Heavyweight Championship in Belfast on 27 February 2016, marking the first time the title changed hands outside of Glasgow and making Damo the first ever Northern Irish-born champion.

Damo defended the title in Ireland, the United Kingdom and the United States against the likes of Drew Galloway, Grado, VSK, Jack Jester and others.

On 31 July 2016, at Shug's Hoose Party III, Damo was defeated for the Championship by Joe Coffey.

In 2016, he wrestled international wrestlers "Speedball" Mike Bailey, Roderick Strong, Dalton Castle, Big Daddy Walter and Matt Sydal.

In 2018, Dain, Wolfe and Young were drafted to SmackDown, where they worked as a stable until the dissolution.

Then, he was drafted again to NXT, where he stayed until his release, in June 2021.

Mackle played as a goalkeeper for his university football side.

He also played rugby union (up to university level), basketball and judo.

He stated that as a child he was attracted to professional wrestling because of the "larger than life" personas and face paint of wrestlers such as Sting and The Ultimate Warrior.

He cites fellow countryman Fit Finlay as a huge influence on his wrestling style and inspiration for his success.

Mackle began his training with Scottish Championship Wrestling, before moving on to train with the SWA/NWA Scotland under Robbie Brookside (now a trainer at WWE NXT) and others.

Of Brookside, he stated; "I don't think there is enough hyperbole to explain how good a coach he is...I can't think of a better coach I'd met in any sport".

After training at NWA Scotland, Mackle debuted for the Scottish Wrestling Alliance at the age of 20 under the ring name Damian O'Connor.

He originally wrestled in Scotland and the North of England as a tag team called "Britain's Most Wanted" with Scott Renwick.

Together the two won a variety of tournaments and tag team championships in promotions such as SWA (4 times), W3L (2 times), SSW and 3CW.

On 11 November 2018.

O'Connor (as Killian Dain) returned to ICW for one night only, defeating Mikey Whiplash.

After leaving WWE, Damo returned to ICW under his original name in 2021.

He would feud with Andy Wild, going to a twenty-minute time limit draw at Fear & Loathing XIII before Wild defeated Damo in a steel cage match at Barred II 24 April 2022.

In 2023, Damo challenged Leyton Buzzard twice for the ICW World Heavyweight Championship.

On ICW Fight Club they went to a no-contest when Andy Roberts interfered.

Damo was given a rematch in a Three Way Dance at ICW's Get The F Out! PPV but was eliminated from the contest by Roberts.