Celtic F.C. supporters

[92] A study of stadium attendance figures from 2013 to 2018 by the CIES Football Observatory ranked Celtic at 16th in the world during that period, with the proportion of the distribution of spectators in Scotland at 36.5%, the highest of any club in the leagues examined (Rangers were not far behind at 18th place globally and 27.4% of national audience share).

[93] The Scottish Cup final in 1937 between Celtic and Aberdeen at Hampden Park was watched by a crowd of 146,433, which is a record for a club match in Europe.

[94] In 1970, Celtic's 'home' leg of their two-legged European Cup semi-final tie against Leeds United was played at Hampden Park to accommodate the expected large attendance.

A 136,505 crowd watched Celtic win 2–1 on the night,[95] a record attendance for a competitive European club tie that stands to this day.

[96] The club's large travelling support make Celtic a popular choice of opponent for English-based footballers to select for testimonial matches.

[112] "The clubs have attracted the support of opposing factions in the political difficulties of Northern Ireland, which intensified the rivalry in Scotland.

Admissions to hospital emergency rooms have been reported to increase ninefold over normal levels[116] and journalist Franklin Foer noted that in the period from 1996 to 2003, eight deaths in Glasgow were directly linked to Old Firm matches, and hundreds of assaults.

[116][117] Occurrences of serious crowd trouble between Celtic and Rangers supporters stretches as far back as the 1909 Scottish Cup final, which was contested by the two sides.

Despite public expectations, no extra time was played and in response thousands of supporters from both sides invaded the pitch to vent their frustration, causing £1,000 of damage (a substantial sum in the 1900s, equivalent to around £120,000 today).

[118] Both clubs petitioned the Scottish Football Association to have the tie abandoned and their demands were met when officials decided the match would not be replayed.

[119][120] Both sets of fans fought an on-pitch battle in the aftermath of Celtic's 1–0 victory in the 1980 Scottish Cup final at Hampden Park.

[121] In January 1988, Mark Walters became the first black footballer to play for Rangers; he made his debut in an Old Firm game at Parkhead and was subjected to racial taunts from Celtic fans, some of whom also threw bananas towards the pitch.

[125] Celtic partnered with Rangers to form the 'Old Firm Alliance' in 2005, an initiative aimed at educating children from across Glasgow about issues like healthy eating and fitness, as well as awareness of anti-social behaviour, sectarianism and racism.

[130] In April 2012, the general secretary of the Celtic Supporters Association said he was "genuinely sorry" after tweeting that it was a "problem" that the Protestant workers who built the Titanic "didn't sail on it".

[141][142] In December 2013, the club were fined £42,000 by UEFA for an "incident of a non-sporting nature" in relation to a display shown by a section of the Celtic support before their Champions League group stage tie against Italian side AC Milan.

After the disciplinary hearing, the club issued a statement in which they condemned the banners and stated that the actions of a "small minority must stop".

[145] In November 2012, the Green Brigade organised a full stadium pre-match card display against Barcelona to celebrate Celtic's 125th anniversary.