Growing up there were two kinds of Gremlins (besides the model of car, that is). There was a one you didn't feed after midnight in the movies and there was the one that was immortalized in cartoons. That gremlin came from WW2 airplane mechanics. If something weird went wrong with a plane, they blamed it on invisible creatures called Gremlins. Roald Dahl, the author of Charlie and the Chocolate Factory was one of the original creators of the cartoon Gremlin. In fact, there were discussions with Disney into making the cartoon gremlins into a feature film during the early years of Disney Animated Movies. Alas, this is one of the shelved Disney projects.
Here is a photorealistic version of what a gremlin might look like if they were real. Don't look at this before going to bed!
Artist Notes - I used a photo I found off the internet for the face and added a nose, fangs and bottom jaw of a bear. I used CorelDraw X5 and Corel PhotoPaint X5 to combine the photo elements and add color.