Slavs
Standardised Slavic languages that have official status in at least one country are: Belarusian, Bosnian, Bulgarian, Croatian, Czech, Macedonian, Montenegrin, Polish, Russian, Serbian, Slovak, Slovene, and Ukrainian.
Yugoslavs
Since the late 18th century, when traditional European ethnic affiliations started to mature into modern ethnic identities, there have been numerous attempts to define a common South Slavic ethnic identity. The word "Yugoslav", meaning "South Slavic", was first used by Josip Juraj Strossmayer in 1849. The first modern iteration of Yugoslavism was the Illyrian movement in Habsburg Croatia. It identified South Slavs with ancient Illyrians and sought to construct a common language based on the Shtokavian dialect. The movement was led by Ljudevit Gaj, whose script became one of two official scripts used for the Serbo-Croatian language.