Melmacians were a species that lived on the planet Melmac before it was destroyed. Their physical features usually included a long snout, and a furry body. Melmacians only had four fingers in each hand, yet they had eight stomachs. The heart of a Melmacian is located in their ear. The usual height of a Melmacian was roughly 3 ft. tall, although ALF's relative Morris Shumway was the shortest Melmacian, meausuring 1 ft. 7 in. All Melmacians die at the same age, 650. All Melmacians favorite food was cats, but they also liked seafood. Their technology was far more advanced than our own, with flying cars, and light speed space travel. 90% of Melmacians were under the height of 3 feet (0.91 m), but were over the weight of 400 pounds, since their fur was very dense. Melmacians were immune to diseases due to the inclusion of the Carl Shrub (ragweed) in their diet. There are only four known survivors of Melmac's destruction: Gordon Shumway (ALF), Skip, Rhonda (ALF's girlfriend), and Blinky (ALF's cousin).
- In the Project ALF, one characters states all seven of ALF's stomachs must be full when he's being carried away. However through ALF it's clearly stated they have eight.
- Throughout ALF, Gordon Shumway mentions that Melmacians are members of the galactic community. However in ALF: The Animated Series, the Melmacians don't seem to aware of other alien races, this is somewhat odd since ALF clearly mentioned his race being into contact with other races. It might be stranger still if Larson Petty's group were aliens from another world, though they might be just breed of Melmacian.
- Also the ALF: The Animated Series seems to show the Melmacians are space-faring skills are somewhat new, as Melmacians haven't colonized numerous other worlds such as Dave.