Johann Bernard Theodor Altum (31 January 1824, Münster, Province of Westphalia – 1 February 1900, Eberswalde) was a German Catholic priest, zoologist, and forest scientist.
He studied philosophy and theology in Münster, and was ordained as a priest in 1849. Later, his interests turned to zoology, a discipline that he studied under Johannes Peter Müller and Martin Lichtenstein in Berlin. From 1859 he was a lecturer at the University of Münster, then relocated in 1869 to the Academy of Forestry in Eberswalde as a successor to Julius Theodor Christian Ratzeburg.
In his earlier work, his research primarily dealt with mammals and birds; after moving to Eberswalde, his studies were largely in the field of forest entomology.
Examenskommission des Ministeriums für Landwirthschaft, Domänen und Forsten (Berlin), October 1893 (Altum is the third seated member from the left).
From 1893 to 1900 he was president of the German Ornithologists' Society.
- Homeri cum Aeschyli, Sophoclis, Euripidis comparantur, (dissertation), Berlin 1855.
- Winke zur Hebung des zoologischen Unterrichts (a zoology instruction manual), Münster 1863.
- Die Säugetiere des Münsterlands, Münster (Mammals of "Münster country"), 1867.
- Der Vogel und sein Leben, Münster 1868 (Birds and their lives); published in several editions, 7th edition 1903.
- Forstzoologie (Forest zoology; volume 1: mammals, volume 2: birds, volume 3: insects; general insects and beetles).
- I. Säugethiere. Second improved and enlarged edition, published by Julius Springer, Berlin 1876.
- II. Vögel. published by Julius Springer, Berlin 1873.
- III. Insecten. 1. Abth. Allgemeines und Käfer. Second improved and enlarged edition, published by Julius Springer, Berlin 1881.