Frumpkin

Frumpkin is the familiar of Caleb Widogast. Caleb usually summons him in the form of a Bengal cat. As a companion, he is controlled by his summoner, Liam O'Brien, with assistance and communication from the Dungeon Master, Matthew Mercer.

As a familiar, Frumpkin can appear, disappear, and/or reappear at Caleb's whim (requires one action). Caleb can issue telepathic commands to Frumpkin. Caleb can transfer his senses to Frumpkin, though this renders Caleb's body temporarily blind and deaf. When Frumpkin loses all hit points or when Caleb wants to change Frumpkin's form, Caleb can cast Find Familiar again to bring Frumpkin back or change his form.

Background
Caleb first summoned Frumpkin a few years prior to the campaign. Frumpkin was created in the form of Caleb's previous family cat, which he was also named after. He served as Caleb's only friend for a few years before meeting Nott in prison. Caleb considers Frumpkin to be very important to him, and seems to view him as an emotional support at times.

Recalling a previous adventure, Frumpkin had taken the form of an octopus and was used as a cushion to break Nott's fall out of a burning building.

Forms
Although Frumpkin's base form was that of a cat, through the Find Familiar spell Caleb could change his form into various creatures including that of a:
 * Sparrow
 * Octopus
 * Peregrine Falcon
 * Owl
 * Spider

Trivia

 * Liam shared his vision of Frumpkin on Instagram (source).
 * Frumpkin disappeared in due to a gnoll attack reducing his bird form's hit points to zero.  marked Frumpkin's first full episode absence. In the episode following this absence, Caleb resummoned Frumpkin in his cat form. Frumpkin was kicked by a guardsman while trying to get into the Spires and his hit points were once again reduced to zero.
 * Caleb has stated that Frumpkin is never upset over his deaths and has a good sense of humor when it comes to them.
 * The origin of Frumpkin's name comes from a cat of the same name that Liam had when he was a kid.
 * Frumpkin does not require food or drink. However, he will do so to please his master, such as when he drank from a bowl of milk given to him by Caleb.
 * According to Caleb, Frumpkin prefers his cat form.