The discovery of the Zentradi race —giant, humanoid aliens genetically engineered for military conquest— prompted the development of the variable fighters' Battroid mode by the U.N. Spacy. Although humanity hadn't yet met any Zentradi, the discovery of the SDF-1 Macross and its accommodations for humanoid giants justified the development of a weapon that could enable mankind to fight the aliens on their own environment (Battroid mode) on the ground (Gerwalk mode) and the air (Fighter mode). Thus, research into alien OverTechnology culminated in the development of the variable fighters for the U.N. Spacy.
They are capable of transforming from aircraft (Fighter mode) into humanoid robots (Battroid mode). Most (but not all) can also transform into an intermediate mode called GERWALK (ガウォーク Gauōku?, Ground Effective Reinforcement of Winged Armament with Locomotive Knee-Joint), similar to the Fighter mode, but with the legs and arms of Battroid mode, making it capable of flight, walking and using hand-held weapons that are accessible in the Battroid mode, GERWALK mode can also allow Variable Fighters to land on hard terrain. A lot of Variable Fighters are capable of spaceflight but not all of them are. Battroid mode is also known as "B-mode". (SDFM: "Countdown")
Since the first TV anime series, each and every variable fighter for all the Macross productions has been designed by Shōji Kawamori (with contributions from Kazutaka Miyatake in some models). Only the variable fighter designs for Macross II were created by the creative team of Junichi Akutsu, Jun Okuda and Koichi Ohata, with no involvement from Kawamori.