Johan Caspar Mylius (22 October 1776 – 15 September 1852) was a Danish military officer and landowner.

He was appointed as chamberlain in 1840 and ennobled under the name de Mylius on 14 October 1840.

He was appointed as captain á la suite in Nordre Sjællandske Landeværnsrgmt in 1802. artillery captain in 1803, Kompagnichef in Landeværnet in 1806, Kompagnichef in the Artillery in 1808.

Mylius was an alternate at the Stænderforsamlingen in Viborg in 1835-40 and represented at the assembly in 1838.

Mylius owned Stamhuset Rønninge Søgård (1831–40), Kattrup (1800–04), Estruplund (1806–51), Mylenberg (1813), Aarupgaard (Slet Hrd.