He is described as being a cross between man and beast, having long arms, covered with fur and leaves, and ever hungry but really "just a sort of a, kind of a thing". His demeanor is extremely loyal and caring, almost to a fault. His manner of speech is filled with rhymed pairs of words ("crunchings and munchings", "smackings and whackings", "sneakings and peekings", etc.), and redundant phrases ("see with lookings!"); he refers to himself in the third person. Gurgi is humble and loyal toward his human companions, at first submitting even to Taran as a "noble lord".
Gurgi is one of the few characters to appear in all five books of the series, the others being Taran, Fflewddur, Dallben and Coll.
In The Book of Three Taran first meets Gurgi in his quest to locate Hen-Wen, the Oracular Pig. At first Taran is disdainful of Gurgi, believing him to be more of a nuisance than anything else. By the end of the book he learns the value of true companionship.
In The Black Cauldron, Gurgi, along with Princess Eilonwy, sneakily follows the Companions to the Black Gate of Annuvin. Gurgi would accompany the Companions to the Marshes of Morva and eventually be the one to find the Black Cauldron.
In Taran Wanderer, Gurgi loyally follows Taran on what might be the most important quest of his life, the search for his true identity (who his parents were, etc.), and proves to be a true friend.
In The High King, Gurgi's bravery is proven from beginning to end and when all is said and done, he must make the hardest choice of all.
According to a 1999 publisher's note, quoting Alexander on The Chronicles, "'The people in it were born, like most children, at unlikely and inconvenient times.. Gurgi, for example, appeared in the predawn hours. ... Suddenly there he was, with his groanings and moanings, looking like a disordered owl's nest."
According to Alexander, nearly all of the proper names in Prydain are from Welsh myth or history, perhaps all except Eilonwy and Taran. There are several characters named Gurgi in Welsh legend, the most important of whom was Peredur's brother.
There used to be a restaurant in Walt Disney World's Magic Kingdom named after Gurgi, Gurgi's Munchies and Crunchies, in Fantasyland. It closed in 1993.  To this date it has been one of only two vendor/attraction with a Black Cauldron theme at any Disney theme park. The other was an attraction; "Cinderella Castle Mystery Tour" at Tokyo Disneyland, which has also since closed in 2006.
- Some speculate that Gurgi may in fact be one of a species of creatures; Orgoch, Orddu and Orwen have referred to him as "the Gurgi," (or "a Gurgi"), though they were corrected that Gurgi is his name
- The cover on one edition of The Black Cauldron shows Gurgi looking like a raggedy humanoid with bushy hair and thin limbs, almost like a starving vagrant. Another has him illustrated similar to a Chimpanzee.
- Prydain enthusiasts tend to agree that Gurgi is probably some sort of primitive primate, given his affinity with animals and his agility.
- Gurgi possesses a magical wallet, a gift from Prince Gwydion, which provides an indefinite supply of nourishing, though somewhat tasteless and dry food.
- While his mount has no name per se, he is often seen riding a shaggy pony.
- Gurgi's performance in the animated movie would go on to inspire Andy Serkis when portraying the Lord of the Rings character Gollum in Jackson's rendering of the books by Tolkien, both in the Rings Trilogy and the prequel trilogy around The Hobbit.
- Alexander, Lloyd. The Book of Three
- The Black Cauldron (Henry Holt, 1999), "About the Author", [page 181].
This is from the first paragraph of "About the Author", which differs from volume to volume in the 1999 reissue, and precedes five 1973 paragraphs essentially unrevised. (The Foundling and Other Tales of Prydain, 1973).
- Lloyd Alexander Interview Transcript Archived 2011-10-03 at the Wayback Machine (1999). Interview with Scholastic students. Scholastic Inc. Retrieved 2009-04-17.
- Alexander, Lloyd. The Black Cauldron