In addition to McCullough's dogged, relentless attacking style,[4] he was renowned for his durable chin, having fought two of boxing's biggest punchers in Naseem Hamed and Érik Morales, and gone the full distance with both of them.

During his bout with Morales in 1999, HBO commentator Larry Merchant joked, "If you look in the dictionary, under 'Tough Irishman', you'll find a picture of Wayne McCullough".

As an amateur living in the staunchly loyalist Shankill Road area of Belfast, he was selected by the island-wide Irish Amateur Boxing Association to participate in the 1988 Summer Olympics in Seoul, Korea, and asked to carry the Irish flag as the youngest member of the team (aged 18).

A technical problem with the public address system made it impossible to play the recording of the song "Danny Boy", used instead of an anthem for medalists from Northern Ireland.

McCullough always fought in neutral colours and did not have national anthems played at his fights; his supporters in Northern Ireland include Protestants and Catholics.

In each of those exciting "Fight of the Year" contenders, he broke his opponent's lengthy run of KO wins while taking them the distance.

Morales stated that McCullough gave him one of the top three fights of his career and almost quit on his stool after the 9th round (according to Ring magazine).

McCullough flew back to Las Vegas and was advised by the Nevada Commission to visit the neurosurgery department at UCLA for a more thorough investigation.

After a very public battle, the BBBC could no longer deny him a licence and later that same year McCullough stepped back into a British ring under the Frank Warren Promotions banner.

[7] Thereafter he had mixed success, winning five fights but losing to Scott Harrison and Mexican world champion Óscar Larios on two occasions.

[citation needed] In 2007, McCullough joined the Ultimate Fighting Championship organisation as a PR associate, to promote Mixed Martial Arts (MMA).

In 2007 McCullough signed to fight Spain's Kiko Martínez who had just defeated Bernard Dunne at the Point Depot, Dublin for the European super bantamweight title.

[12][11] Martínez was given a couple of hours to shed the excess weight, but did not return to weigh in again and the scales were closed by a BBBC official.