The following characters appear in Fraggle Rock, its animated spin-off, and all related projects.

Fraggles The Fraggles are anthropomorphic creatures, about tall, with fur in a wide variety of colors and a tail with a tuft of fur on the end. They live in a network of caves called Fraggle Rock, populated by a variety of creatures, and seeming to connect to at least two different worlds in separate dimensions of time and space. Fraggles spend much of their carefree lives in play, exploring their worlds, and generally enjoying themselves. However, at the same time they maintain a complex culture and society, with each individual having rights and responsibilities. They have basic skill with tools and with rudimentary machinery, and the concept of war is known to them (although wars between Fraggles are very rare). Fraggles live on a diet of vegetables, especially radishes. If individuals touch their heads together before falling asleep they can "share dreams".

Principal Fraggles Five fraggles are at the center of the series: Gobo, Mokey, Wembley, Boober and Red. They form a tight-knit group of friends, and each has a distinct personality.

Gobo Fraggle

Gobo Fraggle (performed by Jerry Nelson in the original live-action series, John Tartaglia in Fraggle Rock: Rock On! and Fraggle Rock: Back to the Rock, voiced by Townsend Coleman in the animated series) is the "leader" of the five main Fraggles. He has the mindset of a young teenager and unusually level-headed and practical for a Fraggle, preferring to control most situations. He plays a guitar (made from a gourd) and often goes on trips to explore the lesser-known tunnels of Fraggle Rock, apparently more out of a sense of obligation to, and admiration for, his Uncle Traveling Matt than from personal inclination, but he nevertheless enjoys these adventures. An unfailing pragmatist, he resists the influence of his friends. Gobo has an orange complexion and purple hair, and wears a yellow sweater with a brown vest: in early episodes he wears a dark magenta cardigan.

During the Outer Space segments (at least in the U.K. version), Gobo is operated by Mike Quinn with Jerry Nelson still performing his voice.

He was designed by Michael K. Frith, and built by Caroly Wilcox and Tim Miller.

Mokey Fraggle

Mokey Fraggle (performed by Kathryn Mullen in the original series, Donna Kimball in Fraggle Rock: Rock On! and Fraggle Rock: Back to the Rock, voiced by Mona Marshall in the animated series) is a highly spiritual and artistic hippie-type Fraggle who usually remains quiet and contemplative, though even she can get annoyed from time to time. Mokey often enjoys painting and writing poetry, although, according to the episode "Mokey's Funeral", her friends, Gobo, Boober, Wembley, and Red, do not always enjoy listening to her poems, especially ones about death or unusually long ones about friendships. She functions as the optimist of the group, trying to see the best in everyone and everything, and comforting her friends when no such "bright side" can be found. According to episode 15, Mokey can make friends quite easily because of her optimistic personality. Though spiritual and serene, Mokey has the dangerous job of procuring radishes from the Gorgs's garden. Mokey has mauve skin and light blue-green hair. She wears a greyish brown robe-like sweater and later an actual turtleneck sweater underneath the robe-like sweater starting in "The Great Radish Famine." She also wears the pop-top from a soda can as a necklace pendant. Mokey Fraggle's puppet regularly switches back and forth between live hands and rod hands, depending on the requirements of the scene. During those times, Mokey's right hand is usually performed by Trish Leeper. Also, she is the only Fraggle character to have moveable eyelids which open wide when scared, excited, or surprised. Mokey thinks more about the heart and is the oldest of the Fraggle group, serving as a den mother. In one episode, Mokey proved herself worthy of joining Cantus and his minstrels, but ultimately chose to remain with her friends. She was designed by Michael K. Frith, the husband of Mokey's performer Kathryn Mullen, and built by Jan Rosenthal.

Wembley Fraggle

Wembley Fraggle (performed by Steve Whitmire in the original series, John Tartaglia in Fraggle Rock: Rock On!, Jordan Lockhart in Fraggle Rock: Back to the Rock, voiced by Bob Bergen in the animated series, Frankie Cordero in Fraggle Rock: Rock On!) is Gobo's roommate and best friend. He is the youngest of the Fraggle Five. While kind, he often appears nervous and pathologically wishy-washy; a his name has become Fraggle slang for an indecisive person, while a variant on his name, "Wimble", is used to describe constantly changing points of view. However, his insistence on seeing all sides of a situation is suggested to grant him especially strong empathy. Starting with the episode "The Thirty-Minute Work Week" and in later episodes, Wembley works with the fire department as their siren. Wembley looks greenish-yellow, with yellow hair. He wears a white shirt with palm trees on it (sometimes two identical one, as a gag about his indecisiveness) which he refers to as his "banana tree shirt". As quite a talented percussionist, he often plays bongo drums.

He was designed by Michael K. Frith and built by Rollie Krewson.

Boober Fraggle

Boober Fraggle (performed by Dave Goelz in the original series, John Tartaglia in Fraggle Rock: Rock On!, Frank Meschkuleit in Fraggle Rock: Back to the Rock, voiced by Rob Paulsen in the animated series, Dave Goelz in Fraggle Rock: Rock On! and Fraggle Rock: Back to the Rock) is the smallest Fraggle and the most intelligent, though unfortunately often depressed and worried as a result. He prefers to live alone and his eyes are usually not visible. Boober almost always expresses a nervous, cautious attitude, and displays hypochondriac tendencies and he deeply ingrained superstitions he struggles to overcome He has so much knowledge that he is actually a capable medic to the other Fraggles, as evidenced in the later seasons. He is fond of cleaning and especially laundry; a running gag depicts him as tending to socks, which no Fraggle visibly wears(he might collect them). Othewise, Boober is an avid reader, likes to share his talent as a chef, and enjoys playing Blues music with his harmonica. Boober is greenish-blue (befitting his personality) with reddish-orange hair, and usually wears a red hat and brown scarf.

He was designed by Michael K. Frith and built by Leslee Asch.

Red Fraggle

Red Fraggle (performed by Karen Prell in the original live-action series, and Fraggle Rock: Back to the Rock and voiced by Barbara Goodson in the animated series) has an exuberant and athletic nature in contrast to her best friend Mokey. She is one of the best swimmers among the Fraggles. Red has a yellowish orange hue, red hair, and wears a red sweater. She is also highly cynical of her friends' plans and ideas, and often teases Gobo about his Uncle Traveling Matt (occasionally yawning while he reads the postcards, or incensing Gobo by calling Matt's adventures "Fiction", "Fairy Tales", etc.). While on the surface, she tends to be competitive, stubborn, arrogant, and rather insensitive, on the inside, Red has proven to be one of the friendliest of Fraggles, perhaps second only to Wembley. Red, like Gobo, wants to be in control, and there is often friction between them over who should be the one in charge (although she has admitted she secretly admires Gobo, and the two are mostly playful with each other). During the course of the show, Red and Mokey become roommates; they get off to a rocky start before improving their friendship.

Mo Rocca described her on VH1's I Love the 80s: Strikes Back as the "buck the establishment Fraggle" (comparable to Peppermint Patty of the Peanuts Gang).

She was designed by Michael K. Frith and built by Rollie Krewson.

Uncle Traveling Matt

Uncle Traveling Matt (performed by Dave Goelz in the original series, John Tartaglia in Fraggle Rock: Rock On!, Frank Meschkuleit in select episodes of Fraggle Rock: Back to the Rock, Kevin Clash in select episodes of Fraggle Rock: Back to the Rock, voiced by Patrick Pinney in the animated series, Dave Goelz in Fraggle Rock: Rock On! and Fraggle Rock: Back to the Rock) is Gobo's famous (as well as pompous, clumsy, and absent-minded) explorer uncle, who spends most of the series in "Outer Space" (the Fraggles's perspective of the human world) and sends postcards back to his nephew describing his adventures there. He interacts with and often ends up interfering with the daily lives of humans, known to Fraggles as the "Silly Creatures". He sometimes refers to himself as "Matthew": he identifies the room filled with entrances to "Outer Space" as the "T. Matthew Fraggle Room." Matt is well-meaning but clumsy and completely oblivious to the world around him; his woefully incorrect perceptions of the human world provide much of the humor for his character. His name puns on "traveling matte", the "green screen" technique used to produce his film segments.

Uncle Traveling Matt was designed by Michael K. Frith and built by Tim Clarke. Dave Goelz, also the performer of Boober, was cast to play the character.

As a child, Matt was raised by his Uncle Gobo, who resembled an older version of himself. He dreamed of his following in his uncle's footsteps as an explorer, though Uncle Gobo did not approve of Matt's dreams. During a famine in Fraggle Rock, when the Fraggles run out of mushrooms, their primary food source, Matt inadvertently discovered radishes in the Gorgs' garden. By the start of the series, Matt is already a well-known and respected explorer in Fraggle Rock. The first episode begins with him exploring the last uncharted area in the Rock. Here, he discovers an entrance leading into the home of the human Doc. Matt, now choosing to go by the name "Traveling Matt", leaves Fraggle Rock, sending postcards back to Gobo in which he recounts his discoveries in Outer Space. Gobo must journey into Outer Space, and get past Doc's dog Sprocket, in order to retrieve these postcards. Matt remains in Outer Space for most of the series, only occasionally returning to Fraggle Rock. This changes in the episode "Uncle Matt's Discovery", when Matt discovers a cave he names the T. Matthew Fraggle Room, which contains a number of portals that lead to various locations in Outer Space. While he continues his explorations in Outer Space, Matt returns to Fraggle Rock more often from this point on, telling Gobo of his exploits in person instead of sending postcards.

In a 2006 interview, Matt's performer Dave Goelz discussed the three character flaws that define Matt's personality: his misperception, his clumsiness (created by Goelz to make taping Matt's segments more interesting), and his denial of the first two flaws. As Goelz later said in a 2011 interview: “The original concept for him was that he went out and misinterpreted everything and then sent postcards back that we saw on video, where he described the outside world in a distorted way. I just didn't think it was very funny, so I started adding two other components. I started adding clumsiness so he was also physically an inept explorer. And then I added this emotional disconnect. So when he wrote back to his nephew, he would say, "I decided to leave the shop." In actuality, you see him being drop-kicked out of the place and flying through the air and hitting a wall. That aesthetic started to become part of the material, and it was written in as we developed it."