A well-known example is the Arab Socialist Ba'ath Party, established as an Arab nationalist and socialist party aspiring to pan-Arab political union.
The party's central governing body, the National Command, included representatives from its organisations in all the Arab countries where Ba'athists had a significant presence.
Each branch of the party, in turn, had a local governing body, the Regional Command, and although practical power became centred in the Syrian and Iraqi Regional Commands and the National Command of each faction assumed an essentially symbolic role, the party split in 1966, with different factions taking control in Syria and Iraq, each faction retained a pan-Arab structure.
In a broad sense, global movements such as communism, socialism, and Islamism have transnational qualities, but in most such cases the party organization is separate in each country, with the transnational aspect being one more of consultatation and coordination, often through political internationals.
One notable exception to this rule is the Progressive Labor Party (United States), which views proletarian internationalism as requiring that they set up party collectives all over the globe.