Melmacian Cockroach

"Brian: Look it has blue eyes? ALF: Naturally, it is a cockroach."

- Brian Tanner and Gordon "ALF" Shumway

The Melmacian Cockroach is a blue-eyed, non-sapient insectoid commonly found on planet Melmac. Although naturally tiny, they can grow to the size of a Human, or even bigger, when exposed to certain earthly chemicals, including insecticide.

After Melmac was destroyed, a Melmacian Roach, named Rodney by ALF and Brian, escaped to Earth in ALF's spaceship and became huge and aggressive after the Tanners' attempts to kill it. Eventually, ALF discovers a substance that is lethal to the Cockroach: perfume.

Since Melmac no longer exists, it's possible that Rodney was the last member of his species, meaning the Melmacian Cockroaches are now extinct.