" Muck to the rescue!" and "Let's get mucky!"
Muck is a red dump truck fitted with a bulldozer blade and caterpillar tracks. Muck often acts before thinking and subsequently gets in trouble for it. His/Her machine-type is referred to as a "digger dump truck".
Muck is friendly and loves getting dirty. He/she does not like taking baths that much but takes them when he/she feels like it, or when he/she knows it is important. Muck is afraid of the dark, but he/she learns to be calm. Muck is also kindhearted, and he/she is sometimes naughty, but he/she learns his/her lesson in the end.
Muck is a red dump truck with an additional bulldozer blade, caterpillar tracks and a shape-shifting mouth. In the original series, his/her headlight eyes are able to turn 360 degrees.
- Season 1 Scoop Saves the Day ( debut), Bob Saves the Hedgehogs, Pilchard in a Pickle, Muck Gets Stuck, Wendy's Busy Day, Bob's Bugle, Buffalo Bob, Travis Paints The Town, Travis and Scoop's Race Day, Bob's Birthday, Naughty Spud, Scary Spud and Bob's Barnraising
- Season 2 Spud The Spanner, Wallpaper Wendy, Runaway Roley, Bob's Big Surprise, Dizzy's Statues, Lofty to the Rescue, Wendy's Big Match, Tea Set Travis, Dizzy's Birdwatch, Clocktower Bob, Pilchard Goes Fishing, Wendy's Tennis Court and Bob's White Christmas
- Season 3 Bob's Boots, Mucky Muck, Bob's Day Off, Magnetic Lofty, Roley's Tortoise, Special Delivery Spud, Pilchard's Breakfast, Scoop's In Charge, Scoop Has Some Fun, Dizzy's Crazy Paving, Spud and Squawk, Muck's Sleep-Over and Trailer Travis
- Season 4 Roley and the Rock Star, Scoop's Stegosaurus, Sneezing Scoop, Roley's Animal Rescue, Scarecrow Dizzy, One Shot Wendy, Spud Lends A Hand, Bob and the Bandstand, Farmer Pickles' Pigpen, Bob on the Run, Forget-Me-Knot Bob, Scruffty The Detective and Watercolor Wendy
- Season 5 Scruffty's Big Dig, Inspector Spud, Cock-A-Doodle Spud, Wendy's Surprise Party, Muck's Monster, Spud the Dragon, Pilchard Steals the Show, Bob's Hide, Bob's Auntie, Bob and the Big Freeze, Clumsy Roley and Eskimo Bob
- Season 6 Bob's Pizza, Bob's Metal Detector, Mr. Beasley's DIY Diaster, Wendy's Removal Service, Lofty and the Rabbits, Lofty and the Giant Carrot, Bob's Egg and Spoon Race, Trix's Tiles, Mr. Sabatini's Smashing Day, Roley to the Rescue, Spud's Big Splash, Spud the Musketeer and Wendy's Magic Birthday
- Season 7 Mr. Beasley's New Friends, Spud the Pilot, Trix and the Otters, Speedy Skip, Bob and the Badgers, Bob and the Goalie, Dizzy Goes Camping, Pilchard's Pets, Snowman Scoop, Lofty's Long Load, Hamish's New Home and Dizzy the Sheepdog
- Season 8 Bob the Photographer, Mr. Bentley's Trains, Wendy's Big Night Out, Racing Muck, Mr. Beasley's Noisy Pipes, Lofty's Jungle Fun, Ballroom Bob, Molly's Fashion Show ( cameo), Spud and the Doves, First Aid Molly, Mr. Bentley: Dog Sitter, Travis Gets Lucky and Scruffty On Guard
- Season 9 Bob the Farmer, Mr. Bentley's Winter Fair, Lofty the Artist, Spud's Statue, Pilchard and the Field Mice, Trix's Pumpkin Pie, Where's Muck?, Travis' Busy Day, Muck's Surprise, Skip's Big Idea, Roley's Important Job, Trix and the Bug and Scoop the Disco Digger
- Season 10 Bob's Fresh Start, Lofty's Shelter, Dizzy and the Talkie Talkie, Scoop's Recruit, Where's Robert?, Wendy's Welcome, Roley's New Friend, Two Scoops, Benny's Back!, Spud's Straw Surprise, Off-Road Scrambler, Meet Marjorie, Muck's Mud Hut and Wendy's Party Plan
- Season 11 Scrambler in the Doghouse, Benny's Important Job, Roley's Round-Up, Dizzy the Detective, Two-Jobs Travis, Scrambler and the Colorful Cave, Muck's Convoy, While Bob's Away, Robert Will Play, Bob's Three Jobs and Scoop Knows It All
- Season 12 Sir Muck
- Season 13 Massive Muck, Muck's Drying Tunnel, Benny's Jungle Trouble
- Season 14 Muck's Mootastic Dairy
- Season 15 Roley Brings the House Down, Muck's Machine Wash, Clean As A Whistle Bristle
- Season 16 Super Splasher, An Inspector Calls
Season 1 - Scratch's Hidden Treasures, Scrambler's Best Idea, Scoop the Artist, High Tide For Lofty, Roley's Rovers, Start from Scratch, Night Time Scratch, Lofty and the Monster, Lofty's Helpful Day, Dizzy In Charge, Scoop's Sea Rescue, Scratch's Star Turn, Pineapple Scratch, Scrambler's Stage Surprise, Wendy's Birthday Surprise, Scratch Goes Solo, Dizzy and the Wheelies, Muck's Beach Tower, Here Comes Muck and Scrambler Gets Clean
Season 2 - Lofty And The Diggers Three, Scoop and the Roller Coaster, Rubble and the Seagull Surprise, Roley and the Impossible Bump, Muck's Train to Trouble, A Dinosaur for Scratch, Whizzy Dizzy, Travis' New Garage, Scratch and the Dream Room, Stage Struck Dizzy, Roley and the Fox, Super Scrambler, Bob's Big Bounce, Scrambler and the Clue, Muck and the Old School Wall, Scoop's Big Job, Dizzy Finds a Pirate and Roley and the Seagull
Muck was the second machine bought by Bob after Scoop needed help with excavation and carrying supplies.
Early descriptions of Muck in the US referred to him/her as a bulldozer.
Muck is male in the UK version and female in the US version (prior to the new 2015 series in which Muck stops being female in the US and becomes male in both versions).
Muck says that Dizzy is his/her best friend in When Bob Became A Builder.
Muck's original movement sound effect was a repeating thumping sound.