Arnold Müller (22 June 1884 – 11 April 1934) was an Austrian entomologist who was born and spent his life in what is now Romania.

In 1902 he matriculated from the high school in Bistritz and in the fall of 1902 began to study natural sciences in the University of Klausenburg.

[3] In 1915 Müller obtained his doctorate in zoology from Klausenburger University, and in 1917 he was elected full member of the Royal Hungarian Society for Natural Sciences in Budapest.

[3] After Transylvania was annexed to Romania, Müller extended his entomological research to the areas of the lower Danube and Dobruja.

[7] Müller's main focus was the entomological fauna of his homeland, Siebenbürgen (Transylvania) and with the specimens he collected in his travels.

In Paris his groundbreaking lecture on "The Post-Ice Age Settlement of Transylvania with Special Consideration of the Orthoptera" was well received.

[2] In his extensive research trips to Syria, Palestine and Egypt, the French Pyrenees and Turkey, he discovered a large number of new insect species.

[8] Most of Müller's 25 scientific papers were published in the Verhandlungen und Mitteilungen des Siebenbürgischen Vereines für Naturwissenschaften zu Hermannstadt (Transactions and communications from the Transylvania Society for Natural Sciences in Sibiu), but some works appeared in Hungarian, Austrian and German journals.