Illyricus may refer to:

• Bogumil Vošnjak (1882–1955), pseudonym Illyricus, a Slovene and Yugoslav jurist, politician, diplomat, author and legal historian
• Matthias Flacius Illyricus (1520–1575), a Lutheran reformer
• Pietro Gozze (1493–1564), called Doctor Illyricus, Ragusan Catholic prelate
• Saint Illyricus of Mount Myrsinon in the Peloponnesus (see April 3 (Eastern Orthodox liturgics))
• Thomas Illyricus (1484/5–1528/9), Dalmatian Franciscan theologian and preacher

• Squalius illyricus, a ray-finned fish species
• Astragalus monspessulanus subsp. illyricus, a plant subspecies

• Illyricum (disambiguation)
• Illyrians (disambiguation)
• Illyrian (disambiguation)
• Illyria (disambiguation)