Illyricum may refer to:

• Illyria, a region in Southeastern Europe in classical antiquity, inhabited by ancient Illyrians
• Illyricum (Roman province), a Roman province that existed between 27 BC and 69/79 AD
• Diocese of Illyricum, a diocese of the Late Roman Empire
• Praetorian prefecture of Illyricum, one of four praetorian prefectures into which the Late Roman Empire was divided
• Illyrian Provinces, an autonomous province of France during the First French Empire 1809-1814
• Illyricum sacrum, a classic eight volume historical work, published from 1751 to 1819

• Pancratium illyricum, a flowering plant species
• Polystichum illyricum, a fern hybrid species
• Onopordum illyricum

• Illyricus (disambiguation)
• Illyrians (disambiguation)
• Illyrian (disambiguation)
• Illyria (disambiguation)
• Illyricvm, 2022 historical film with reconstructed Illyrian language