Bert is a hypocoristic form of a number of various Germanic male given names, such as Robert, Albert, Elbert, Herbert, Hilbert, Hubert, Gilbert, Wilbert, Filbert, Fulbert, Norbert, Osbert, Roberto, Roberta, Bertram, Berthold, Bertrand, Umberto, Humbert, Humberto, Alberto, Alberta, Albertine, Albertina, Cuthbert, Delbert, Dagobert, Rimbert, Egbert, Siegbert, Gualbert, Gerbert, Lambert, Engelbert, Bertie, Uberto and Colbert.
Most of these names are early medieval and only a comparatively small fraction remains in modern use.
There is no evidence of the berht element in Germanic personal names prior to the 6th century.
The full form of Old High German beraht is reduced in two ways, by omission of either the second (berht, perht, pert) or the first vowel (braht, praht, brat, prat, brecht).
Early attestations of such names include Ethberictus, Garberictus, and Transberictus mentioned in Hontheim's Historia Trevirensis s. a.