Here You can find a list of airlines which operated in Graz airport.
Thessaloniki - Austrian
Amsterdam Schiphol - KLM Royal
Maastricht Aachen - Lufthansa
Bologna - Lufthansa
Zagreb - Lufthansa
Vienna Schwechat International - Austrian
Zürich - Swiss International
Düsseldorf - Eurowings
Frankfurt am Main - Lufthansa, AirDolomiti
Hannover Langenhagen - Lufthansa
Munich - AirDolomiti, Lufthansa
Nuremberg - Lufthansa
Stuttgart - Eurowings