“Now was that civilized? No, clearly not; fun, but in no sense civilized”|
—The Brain Gremlin
The Brain Gremlin (or just simply Brain) is the main antagonist in Gremlins 2: The New Batch, as he takes over for the film's original antagonist Mohawk following his demise. He's a brown mutated gremlin who wears glasses and later on he wears more formal clothing. He has a well-spoken human voice which he got after drinking a beaker full of a mutagenetic brain hormone serum in the Clamp Center laboratory, which also had the effect of greatly increasing his intelligence. Afterwards, he dressed more like a human, wearing business-like clothing and wearing glasses that had appeared from no known location or source. Although he's a villain, he's very articulate and cultured for a gremlin, though his mischievous nature still prevails. He does not appear to be as destructive as the other gremlins and he appears to be somewhat fascinated by the humans' culture and their way of life.
He drank a potion called The Brain Hormone, created by Dr. Catheter. The hormone made the gremlin go through a seizing transformation, after which his intelligence had expanded. He immediately talks to the scientists in the lab (who are too scared to even respond), "I, wanna, talk a little bit about what's going around in this room because, I think there's some fascinating ramifications here for the future. When you introduce new genetic material of research quality to a life form such as ours, which is possessive of a..a sort of...I hesitate to use the word atavism, but let us say a highly-aggressive nature. For example, for that fellow near the, um, I believe that's a common bat of the order Chiroptera, the only mammal, I might add, capable of true flight".
As he watches Bat Gremlin form, he shows his mischievous, chaotic side. He identifies genetic sunblock, the cure for the Gremlins' weakness of sunlight, which will allow them to escape the building unharmed. He seems to still communicate with fellow gremlins, even while speaking as a human. As he approaches Bat Gremlin, he explains his "potential". He injects genetic sunblock into Bat Gremlin. He encourages Bat Gremlin to fly out and check out the city. Though to the scientists, they believed he was encouraging him to "eat children", either way the group were unsuccessful at stopping Bat Gremlin.
Later, several gremlins attacked and slaughtered people, while the Brain Gremlin helps his team of monsters win, although he doesn't attack people since he develops a fond nature of manners and the desire of having his team civilized.
The Brain Gremlin wanted his species, the Gremlins, to be civilized, or at least his definition of being civilized. He explains this when a Clamp TV show host named Fred and cameraman Mr. Katsuji interview the Brain Gremlin. The Brain Gremlin claims that their reaction is a desire to have civilization and that they were "stumbling along the way". He attempts to show how he wants to be by using an example of a gremlin who's annoying him. To which he reverts to his nature and shoots the fellow Gremlin, while on watching his fellow monsters laugh. Though he admits he found it "fun" but not civilized.
He was later seen singing New York, New York with several gremlins (around 200 to 300 gremlins were inside the building), and they were ready to leave the building. However, when they plan to exit the building so that New York City will no longer have human existence and instead replaced by a civilization of gremlins, Billy Peltzer absorbed a gremlin who drank an electric potion (turning the gremlin into raw electricity), into a phone, then his friends Kate Peltzer and Murray Futterman help him to stop the gremlins. Then Murray sprays the gremlins with water as the Brain Gremlin becomes the first to get blasted by water, and then Billy aims the Electric Gremlin at them. Then the wet gremlins all exploded and melted due to the result of electricity and water. Then the Brain Gremlin tries to finish singing the song New York, New York, with his dying words were "New York, New York," till his voice was gargling again and he lost his human voice, before he fell to the ground dead.
- He is a fan favorite among the Gremlins 2 fans.
- Brain's clothing while singing "New York, New York", like the song, is a homage to Frank Sinatra.
- In the original draft, Brain was supposed to have a different death: After singing "New York, New York", Gizmo shoots a dart that injects him with a helium serum, causing him to bloat like a balloon and float out a window to his doom. This scene was cut and never filmed.
- Brain is the first leader to not be spawned from Gizmo. He was spawned from one of the other gremlins.
- In the novelization of the film, his name was Mr. Glasses.
- He never seems to mention the bat gremlin after its death; though most likely because they could not venture out yet. He didn't know.
- He makes a brief cameo in the Gremlins 2: The New Batch (video game), where he appears in a card where the player chooses to Continue the Game or Quit the Game when he/she pauses. He does not appear in the video game's story however which makes little sense as he is the main antagonist of the film.
- Along with the Vegetable Gremlin, he is the only mutated Gremlin to have become wet in the film, and he most likely spawned more Gremlins. It is unknown what happens to mutated Gremlins if they get wet, as they might pass down the same traits to their clones. He possibly spawned more Gremlins with higher intelligence or he spawned normal Gremlins or neither really since the gremlin foetus' where all killed along with him.
- During the interview scene of Gremlins 2: The New Batch several studio lights are seen shining down on the Brain Gremlin, even though gremlins are harmed by bright light, perhaps the Brain could have injected himself with the Genetic Sunblock as he did to the Bat Gremlin. This could also just be a plot hole in the film.
- In Gremlins 2: The New Batch, he was voiced by the late Tony Randall. In LEGO Dimensions, he is voiced by Christopher Swindle.
- Tim Curry was considered for the voice of the Brain Gremlin but Tony Randall already has the part.