Oneworld is an airline alliance founded on 1 February 1999. The alliance’s stated objective is to be the first-choice airline alliance for the world’s frequent international travelers. Its central alliance office is currently based in New York City. Oneworld is the third largest global alliance in terms of passengers, behind Star Alliance and SkyTeam. Its slogan is: An alliance of the world’s leading airlines working as one.
Source: Wikipedia

Full members and some of their affiliates:
– American Airlines (founding member), including US Airways
– British Airways (founding member)
– Cathay Pacific (founding member), including Dragonair
– Finnair
– Iberia, including Air Nostrum/Iberia Regional
– Japan Airlines
– LATAM Airlines Group
– Malaysia Airlines
– Qantas (founding member)
– Qatar Airways
– Royal Jordanian
– S7 Airlines
– SriLankan Airlines

Former members and some of their affiliates:
– Air Berlin, including Belair and Niki
– Aer Lingus
– Canadian Airlines (founding member)
– Malev
– Mexicana, including MexicanaClick