The Champions League is the updated format of the former European Cup. The first Champions League was in the 1992/93 season and was won by Marseille. No club has ever retained the Champions League in its current format.
If however you mean the first European Cup which was in the 1955/56 season, that was won by Real Madrid, who would then go on to win it another 4 times in a row. Making them the only team in history to win 5 in a row. They have since won another 4 and hold the record with a total of 9.
They won the European cup in 1968 and the Champions league in 1999.
Chelsea have won the Champions league only once. They won their first and only Champions league in 2012.
Borussia Dortmund, the german club, won the Champions League in 1997. It was their very first Champions League triumph.
No American has won the Champions League to my knowledge.
No Chelsea have never won the champion league in their history.
Glasgow Rangers have never won the Champions League.
Liverpool won the Champions League in 1977
Real Madrid won the very first Champions league in 1956. They defeated Stade de Reims 4-3 in the final.
Messi has two champions league medals. First he won in 2006 and second in 2008.