I know this has been made quite e few times. I want to start the series I will make with a video about the world's biggest club international event. So here are the winners:
1955/56 - Real Madrid CF (W1)
1956/57 - Real Madrid CF (W2) - (IR2)
1957/58 - Real Madrid CF (W3) - (IR3)
1958/59 - Real Madrid CF (W4) - (IR4)
1959/60 - Real Madrid CF (W5) - (IR5)
1960/61 - SL Benfica (W1)
1961/62 - SL Benfica (W2) - (IR2)
1962/63 - AC Milan (W1)
1963/64 - FC Internazionale Milano (W1)
1964/65 - FC Internazionale Milano (W2) - (IR2)
1965/66 - Real Madrid CF (W6)
1966/67 - Celtic FC (W1)
1967/68 - Manchester United FC (W1)
1968/69 - AC Milan (W2)
1969/70 - Feyenoord (W1)
1970/71 - AFC Ajax (W1)
1971/72 - AFC Ajax (W2) - (IR2)
1972/73 - AFC Ajax (W3) - (IR3)
1973/74 - FC Bayern Munchen (W1)
1974/75 - FC Bayern Munchen (W2) - (IR2)
1975/76 - FC Bayern Munchen (W3) - (IR3)
1976/77 - Liverpool FC (W1)
1977/78 - Liverpool FC (W2) - (IR2)
1978/79 - Nottingham Forest FC (W1)
1979/80 - Nottingham Forest FC (W2) - (IR2)
1980/81 - Liverpool FC (W3)
1981/82 - Aston Villa FC (W1)
1982/83 - Hamburger SV (W1)
1983/84 - Liverpool FC (W4)
1984/85 - Juventus FC (W1)
1985/86 - FC Steaua Bucuresti (W1)
1986/87 - FC Porto (W1)
1987/88 - PSV Eidenhoven (W1)
1988/89 - AC Milan (W3)
1989/90 - AC MIlan (W4) - (IR2)
1990/91 - FK Redstar Belgrade (W1)
1991/92 - FC Barcelona (W1)
1992/93 - Olympique de Marseille (W1)
1993/94 - AC Milan (W5)
1994/95 - AFC Ajax (W4)
1995/96 - Juventus FC (W2)
1996/97 - Borussia Dortmund (W1)
1997/98 - Real Madrid CF (W7)
1998/99 - Manchester United FC (W2)
1999/2000 - Real Madrid CF (W8)
2000/01 - FC Bayern Munchen (W4)
2001/02 - Real Madrid CF (W9)
2002/03 - AC Milan (W6)
2003/04 - FC Porto (W2)
2004/05 - Liverpool FC (W5)
2005/06 - FC Barcelona (W2)
2006/07 - AC Milan (W7)
2007/08 - Manchester United FC (W3)
2008/09 - FC Barcelona (W3)
2009/10 - FC Internazionale Milano (W3)
2010/11 - FC Barcelona (W4)
2011/12 - Chelsea FC (W1)
2012/13 - FC Bayern Munchen (W5)
2013/14 - Real Madrid CF (W10)
2014/15 - FC Barcelona (W5)
2015/16 - Real Madrid CF (W11)
2016/17 - Real Madrid CF (W12) - (IR2)
2017/18 - Real Madrid CF (W13) - (IR3)
2018/19 - Liverpool FC
By Country:
Spain - 18 Wins
England - 13 Wins
Italy - 12 Wins
Germany - 7 Wins
Netherlands - 6 Wins
Portugal - 4 Wins
Romania - 1 Win
France - 1 Win
Serbia - 1 Win
Scotland - 1 Win