Gordon Shumway, also known as ALF (acronym for "Alien Life Form"), is the protagonist and title character of the American television series ALF and its animated spin-offs, ALF: The Animated Series, and ALF Tales. ALF also starred in the poorly received television film Project ALF, and hosted the short lived talk show ALF's Hit Talk Show. Paul Fusco created and plays ALF, and he also provides the voice for the character. On ALF, Lisa Buckley and Bob Fappiano assisted Fusco with performing the furry brown alien. During the first season of ALF, Michu Meszaros occasionally wore a full costume when full body shots were needed of the character.

Since ALF, the character has appeared in various other media, including television series, comic books, and video games.

Paul Fusco created the character in 1984 using an alien-looking puppet, that he used to annoy his family and friends. Bernie Brillstein was approached to see Fusco's audition with a puppet character but was initially uninterested, having managed Jim Henson for years by that point, and regarding Henson as the best puppeteer in the business. However, Fusco's brief performance as ALF won over Brillstein, who thought the character was hilarious and strong enough to be the focus of a series.

Fusco was notoriously secretive about his character up until the series' premiere. During the show's production, Fusco refused to acknowledge that the puppet ALF was anything other than an alien. All involved with the production were cautioned not to reveal any of ALF's production secrets.

To avoid wear and tear on the principal ALF puppet, the performers rehearsed with a crude early version of ALF, nicknamed "RALF" for (Rehearsal Alien Life Form or Repulsive Alien Life Form). Fusco did not like to rehearse and would often substitute his hand or RALF for the real ALF puppet during rehearsals.

To perform the titular alien on the ALF sitcom, Paul Fusco inserted his left hand into the head of the ALF puppet to perform the character's mouth, leaving his right hand to serve as ALF's right arm. Underneath the trap doors and holes on the set floor, Fusco would be assisted by a second puppeteer, Lisa Buckley, who was responsible for controlling the character's left hand. From off-screen, a third puppeteer, Bob Fappiano, would operate his eyes and other facial features via remote control. In recent years, Paul Fusco's wife, Linda Fusco, has regularly operated ALF's left hand.

When creating ALF's voice, Fusco initially took inspiration from that of Rowlf the Dog, a Muppet character performed by his creator, Jim Henson. Rowlf's gruff voice, though, ended up straining Fusco's vocal cords, which led him to invent a new voice that was much lighter, until it evolved into ALF's voice as it is known today. However, in early episodes of the series, ALF speaks with a voice reminiscent of the earlier, Rowlf-esque voice.

During the first season of ALF, whenever the character had to be seen in full-bodied shots, Hungarian actor Michu Meszaros would don a life-sized ALF costume. However, Meszaros's services became too costly, and the regular ALF puppet would be used for all of his scenes on the show.