Goombas are anthropomorphic shiitake mushrooms who serve as the ubiquitous basic enemy in Nintendo's Super Mario Bros. series of video games. Although there are dozens of variations of Goomba, the basic version is a shiitake mushroom with eyes, dark eybrows scrunched up into a scowl, two upward pointing fangs, and two large brown feet (but no legs). The basic Goomba is not very hard to defeat, wanderning back and forth aimlessly until it is stomped on, fireballed, or otherwise smushed by a wandering plumber. The Goomba has appeared in every single Mario video game to date, and various other media incarnations as well.
The English name Goomba seems to derive from the American slur for ethnic Italians "Goombah," which in turn derives from the Neapolitan dialect's cumpà (standard Italian compare or Spanish compadre), which translates in "mate" or "comrade." However, strangely, the name of the Goomba in Japanese is "kuribō" (クリボー), which loosely as "chestnut guy," even though they are clearly mushrooms. This discrepancy has never been officially explained. The Japanese Wikipedia page simply notes in passing, "They are called chestnut guys, yet they are not chestnuts."