Scuba diver pianist - The "imported music" in the episode "Krusty Love"
Artist at Sea - appeared in "Frankendoodle". He dropped his pencil into the ocean, falling into Bikini Bottom, not having another one. Later he breaks his pencil not having a sharpener. Both of these respond in "NOOOOOOOO!!!!!!!" Played by Doug Lawrence.
Comedy Drummer - appeared in "Prehibernation Week" to alert us to Sandy's bad pun about fly-fishing. (played by storyboard artist Aaron Springer)
Kids of Monkey Lagoon - The kids featured in "The Seven Trials of Monkey Lagoon" in the episode "The Sponge Who Could Fly."
Cavey - A caveman that Patchy found in an iceberg and spent three days thawing him out with his mother's hairdryer in the episode "Ugh". Portrayed by Bill Fagerbakke, the same person who voices Patrick Star.
Patchy's mother - Only referenced in the episode "Ugh".
Tom Kenny - In "Neptune's Spatula" when Neptune opened a curtain to reveal Atlantis he accidentally reveal this guy in the shower. In "Suds", it was possibly his foot that was scrubbed by SpongeBob as part of a treatment. He also portrays SpongeBob, Gary, The French Narrator, and Patchy.
Bodybuilder, A bodybuilder that appeared in "Life of Crime". His only line was "Ja, buns and thighs!" supporting SpongeBob's statement, "All this running is good for your buns and thighs." He (bodybuilder) speaks like Arnold Schwarzenegger, in an Austrian Accent.
T-Rex - a dinosaur who appeared in "Ugh." After the "When Worlds Collide" song, Potty presented the dinosaur to Patchy as a gift. The dinosaur chased Patchy and bit him.
Hans - a hand of a sailor that usually appears in several episodes and has a Dutch accent, but in "Model Sponge", he speaks in an Austrian accent similar to Arnold Schwarzenegger. He first appeared in "Suds", and his name was revealed in that episode too.
Fishermen - a group of human men that appear in "Hooky", casting along the waters of Bikini Atoll. They are very low tempered.
Chumbot - Appeared in "Enemy In-Law". He took citizens hostage and "forced them to eat at the Chum Bucket." Also captured Mrs. Krabs (Mr. Krabs' mom) and then had an affair with her, while Plankton was trying to become her husband and seemingly succeeding but he failed.
Command Module - one of the three robots that Plankton created in "Komputer Overload." It fought with the other two, and was eventually combined with the other two robots but was destroyed along with the others when the plug came off. It is a hair dryer taped to an old-fashioned miniature wind-mill.
Plankton Robot - used by Plankton to rob the Krabby Patty in the episode "Plankton's Army". Mr. Krabs thought that the robot was a part of one of Plankton's schemes, but was not since the robot did not order the Krabby Patty, but inside the "dollar" that the robot gave Mr. Krabs was Plankton. This robot is a citizen of Bikini Bottom. He is voiced by Dee Bradley Baker.
Krab-Borg - appeared in "Imitation Krabs". It was a robot replica of Mr. Krabs controlled by Plankton. It was also used to steal the Krabby Patty recipe, but exploded when SpongeBob inserted a coin into the self-destruct coin slot. It was seen in "New Leaf" along with some other "friends from the past". In the episode "Spy Buddies", Plankton is using the robot again.
Robot SpongeBob- a robot built in the episode "Welcome to the Chum Bucket". Used by Plankton to control SpongeBob's brain in order to reveal the Krabby Patty formula. He is a recurring villain in the video games, but is differently designed, and is somehow arrogant and lazy. SpongeBob is his nemesis.
Robo 2.1- a robot that SpongeBob gave to Patrick in "The Gift of Gum". It follows Patrick around and calls him "master."
SPU31 - appeared in "Komputer Overload". One of Plankton's robots. It squirts water it fought with the other two robots. It has no arms just two legs made of wood
T-119A Compumatic - one of the three robots that Plankton created in "Komputer Overload". It fought the other two robots until Plankton combined the three to create a giant robot. It is a toaster with two legs and one arm.
Anchovies- There are various anchovies in Bikini Bottom. Some are part of the Jellyspotters, led by Kevin C. Cucumber. They mostly say meep. They have huge appetites and are very demanding customers when they show up at the Krusty Krab. Most of Pearl's boyfriends are anchovies, including Octavius Rex. First seen in "Help Wanted". They were voiced by Rodger Bumpass. Lenny and Mable are also anchovies.
Aqua/Lavender Fish - Fish who got sand in his buns ("Ripped Pants").
Black/White Whale - Was buried in the sand and forgotten in the episode "Ripped Pants".
Cephalopod Lodge Members - Very little is known about this group
Fry Fish - Asked for a job application for the Krusty Krab. Mistaken for the Hash-Slinging Slasher after calling on the phone and hanging up in the episode "The Graveyard Shift". Voiced by Dee Bradley Baker.
Truck Driver - Drives a semi-truck in the episode "Pizza Delivery." Does not like break dancers. He is a purple marlin. Voiced by Doug Lawrence.
Old Man - Wrote the memoirs of his life in red ink; a deluge of cranberry juice ruined his hard work. He lives at Shady Shoals Retirement Home and has been seen in a few episodes. He is short and has a long gray beard. He is also a member of the Mild Ones. Voiced by Tom Kenny.
Referee - Refereed the Anchor Toss Competition at Goo Lagoon ("MuscleBob BuffPants"). He kept getting hit by anchors.
King - The king that Squidward was performing for in his dream in "Sleepy Time".
Green Eel - The eel who cut in front of SpongeBob at the ice cream vendor at Goo Lagoon in the episode "Walking Small". Later Plankton made SpongeBob make the eel cry "tears of joy."
The Announcer - The Announcer of the Anchor Toss Competition who appeared in "MuscleBob BuffPants". He asked the Referee how long each person threw
Blonde eel - if fish that wanted to tell him how to tie his shoes, but she couldn't since she is an eel. She appeared in "Your Shoe's Untied."
Octopus Vendor - An octopus who works at a burger/hot dog stall at Goo Lagoon ("Walking Small").
In Nature Pants, he shakes SpongeBob's hand, comically swelling it. In 20,000 Patties Under The Sea, he shrugs when Patrick and SpongeBob run from it screaming.
Unnamed Snail - A snail that appears in Nature Pants. In that following episode, This snail serves as a brief hiding spot for SpongeBob when he is being pursued by Patrick after which, It meows and slithers away. It is very large and has a grey, speckled shell that is covered in coral. It will most likely not be featured in future episodes
Dolly - is a minor character in the movie PC game.
Pirates - A crew of pirates who sold bomb pies in Dying For Pie.
Squid Doodle - Patrick drew this crude 2D drawing of Squidward with the "magic pencil". He only mumbled and shook his fist for about 30 seconds in "Frankendoodle" before he was erased.
Mustache Doodle - Patrick drew a mustache on himself that came to life in Frankendoodle flew away onto Squidward's head and served as his toupee. Later on, Squidward tripped and the mustache flew away.
Rocky - Patrick's pet snail, whom he entered in "The Great Snail Race"; Rocky appeared to actually be a rock, but managed to overcome this setback to win the race. According to Patrick, he "has nerves of steel".