Another series from the "Nagahama trilogy" Daimos gave us another robot buddy. It performed all kind of tasks in the Daimobic -including household chores- and it gave advice and council (often of the "Nobody asked you!" kind).
Masha/Mini Mew of Tokyo Mew Mew is the Robot Buddy crossed with the traditional Magical Girl's Talking Animal. He's a lot more simple-minded and cuter than either, and in the manga he also, under the right conditions, turns into the girls' penultimate weapon.
The Tachikomas in Ghost in the Shell: Stand Alone Complex are the sweetest, nicest little things you've ever seen, replete with childish voice and cute bubbly appearance. They are also armed with machine guns and grenade launchers (with an optional minigun attachment), and won't bat an eyelid (well, so to speak) at the concept of slaughtering entire platoons of bad guys. And yes, they do eventually perform a Heroic Sacrifice (twice).
They also have no concept of work, so apparently killing bad guys is their hobby.
The friendliness is subverted in one episode, showing that they're oblivious to anything being wrong with throwing a dog.
Lockon has his own orange Haro and his Gundams are designed to interface with it. This one is arguably the most intelligent of the bunch as it frequently snarks at Lockon, calls Nena's Haro "nii-san"("Big Brother" in the dub) and mourns the first Lockon's death by constantly calling out to him for a while. In The Movie, it gets a blue companion since Gundam Zabanya is too complicated for just one Haro.
Nena's purple Haro is as foulmouthed as Nena's brother and not only outright insults Lockon's Haro, it even knocks the latter away. Plus its extremely creepy when it starts talking Machine Monotone in Ribbons' voice.
In the second season, Saji is usually accompanied by a red Haro. It even assists him in piloting the O-Raiser and at one point foils a hijack.
Snivel and NSOB from the French series Sillage (known in the US as Wake).
This is more or less the entire point of DC's Metal Men. Complete with the Heroic Sacrifice in their original incarnation, they were all destroyed by the end of every single comic, and the last panel would be their scientist creator quietly picking up all the pieces for reassembly.
The Star Wars droid pair of C-3PO and R2-D2, with C-3PO's fluency 'in over 6 million forms of communication' and R2-D2's seemingly endless supply of gadgets for every conceivable task.
One of the signs that the Rocky franchise had gone completely off the rails was the weird and bewildering subplot in Rocky IV in which Paulie (Rocky's brother-in-law) gets a robot wife.
The robot arms in the movie version of Iron Man. They include one with a grip which saves Tony's life after his new arc reactor is removed, one with a camera that the film sometimes switches to, and the most famous one, the fire extinguisher bot, who is really enthusiastic about his job.
The one with the gripper hand is remarkably clumsy. One wonders why Tony even bothers to keep using him at all, unless you pay attention during the magazine cover montage in the beginning of the film and see that he built that robot when he was in college. The clumsy one, "Dummy" as Tony calls him, is also the fire extinguisher.
Bumblebee in Transformers seems to take this role on occasion. He gives the impression of actively trying to invoke the trope; Sam accuses him of faking muteness at one point to try and be endearing.
The third movie gives an almost darker version of this trope, with Soundwave and Laserbeak being "clients" to the human Dylan. However, it's more of a mutual respect than an actual friendship, as back story reveals that Soundwave respects Dylan because the human has an almost similar personality to his true master, Megatron.
Huey, Dewey and Louie (no, not those three!) in Silent Running are three service robots on the Valley Forge, an American Airlines space freighter.
Robby the Robot in Forbidden Planet epitomizes this trope, and may have done it first in film.
The trope is played with very casually in Funny People. One of the posters of his own movies George Simms has in his house is called "My Best Friend is a Robot". No footage of the film-within-the-film is shown, nor is it ever mentioned in dialogue. We can glean from the poster that it also stars Owen Wilson, but there's no telling whether he or Simms played the robot.
Charlie in Making Contact. He's next to useless, but cute and inoffensive and seems to represent Joey's connection to his dead father in a way since Charlie was given to Joey by his father as a Christmas present.
Kelex and Kelor in Man of Steel, floating droids serving the El family. The former is more prominent.
Robo And Frank is the heartwarming story of a curmudgeonly old burglar who teaches his trade to his robot buddy.
Eliminators has SPOT ("Search, Patrol and Operational Tactician"), a little R2-D2-ish robot that can turn into a ball of energy and fly around and scout the area.
Erek King from Animorphs. But he and the kids have a falling out at the end of the series, because Jake blackmailed him into fighting, which he's programmed never to do. Conversely, the kids blame Erek for the death of Rachel, as Erek drained the Pool ship's weapons. Erek and the Animorphs never reconcile.
Perhaps the Trope Namer, the My Robot Buddy series, by Alfred Slote, features Danny One as the title character.
Tik-Tok from the Oz bookOzma of Oz is the earliest example of this trope.
Christopher Stasheff's Warlock of Gramarye series has Rod Gallowglass' companion Fess, a slightly-malfunctional robot retainer who often wears the body of a Mechanical Horse while on undercover missions.
The drones in books about The Culture by Iain M. Banks are loyal companions, but very deadly if they work for Special Circumstances. If they don't, they usually have attitude problems.
Norby in his titular series by Isaac and Janet Asimov. Telepathy, Hyperdrive, and Time Travel are just a few of his abilities. Incidentally, as it was made in 1985, he may be the first of the Deadpan Snarker bots.
The X-Wing Series, as part of the Star Wars Expanded Universe, has more than a few pilots' astromechs that fit the bill. Corran Horn's droid Whistler offers electronic raspberries when he thinks Corran is being stupid, is packed full of useful programming from the duo's days on the Corellian Security Force, and will refuse to eject when going into a lethal situation. "Face" Loran took a cue from Return of the Jedi and outfitted his Vape with a beer ejector. Myn Donos's droid Shiner was the only other survivor from his original squadron, leading to Donos's Heroic BSOD when he's destroyed. And Lara Nostil's companion Tonin got to become King of the Droids and help take down a Super Star Destroyer.
Galaxy of Fear has DV-9, who feels like his talents are wasted on babysitting and resents this duty, and is the most worlds-weary of the cast, but still feels driven to help his charges and his master however he can. Still, he elects to be Put on a Bus halfway through.
In a Polish sci-fi novel for teenagers Ci z dziesiątego tysiąca (Ones from the Tenth Thousand) by Jerzy Broszkiewicz, the main character, Ion Soggo, has an android friend named Robik, who has accompanied him since early childhood and even changed his form gradually in order to best address a child's changing needs (from a funky humanoid toy to an ordinary human teenager, albeit with formidable strength and computing power). Robik was designed and programmed to be Ion's friend and protector, which became a bit of a problem when he actively sabotaged a rescue mission Ion was involved in, as it put Ion in danger.
In the old series, there was also Kamelion, who was a humanoid robot who, like his name suggests, could impersonate people. Unfortunately, this wasn't used to its full potential because the man who designed the prop (and thus, knew how it worked) died before he could pass the instructions on to anyone else. Thus, he was Put on a Bus every episode up until the one where he was killed off.
Gadget in "The Waters of Mars."
Gadget:Gadget, gadget! The Doctor: Does it have to keep saying that? Roman: I think it's funny. The Doctor: I hate funny robots. [He does mention later that dogs are different.]
In Robin's previous life as a pseudo teen pop singer on How I Met Your Mother, one of her trademarks was a cute little robot sidekick.
On the show Lexx, the disembodied robot head 790 was once a programmed soldier working for the League of 20,000 Planets in the Light Zone, but gained new programming which it received in a process designed to give love slave training to the character of Zev, and ended up tagging along with the crew.
Tom Servo and Crow are the robot buddies of Joel Hodgson/Mike Nelson on Mystery Science Theater 3000, though they're not particularly useful apart from their capacity for wit and sarcasm (and with Crow, that's not always guaranteed).
Andy from Quark was a cowardly robot built by the titular character. He doesn't actually do anything, just complains all the time.
KITT from Knight Rider has the distinction of being a Robot Buddy main character. As such, he gets a lot more personality than your typical Robot Buddy, and gets to make more demands of his partner Michael, often giving Michael orders and expecting them to be carried out.
Twiki from Buck Rogers in the 25th Century. He may not have any internal tools installed, but any droid who can operate a fighter craft designed for humans and do it well in combat is not to be underestimated. Another of his roles (in obvious reference to R 2 D 2) is as an electronic lockpick, which nobody but Buck ever seems to expect an ambuquad to be able to do.
The original Battlestar Galactica had a robotic daggit, which was mostly a Replacement Goldfish but occasionally proved useful for crawling through ductwork or whatever. It had artificial fur and the most obnoxious synthetic bark imaginable.
Cy, from Galactica 1980. In fact he's often viewed as the only good thing about it.
Power Rangers Megaforce, adapting both Goseiger and Gokaiger, edited out both Datas and Navi in favor of its own buddy named Tensou.
Tokumei Sentai Go Busters deserves special mention, as instead of just one Robot Buddy for the team, each Buster has their own "Buddyroid" partner. Jin's partner, Beet J. Stag, can even transform and fight alongside the others as Stag Buster.
Incidentally, his character type is not Robot Buddy. It's Invincible Robot/Super Robot.
Clank from the Ratchet & Clank series, although he's usually more well-grounded than Ratchet.
No list of Robot Buddies would be complete without Floyd from the InfocomInteractive Fiction game Planetfall, called (by those who played the game) one of the most endearing and memorable characters in game history.
Another Floyd appeared in Jet Force Gemini. This one rebelled against the big bad and saved a few tribals but needs you to fix him up again. A friend can even control him afterwards to help fight enemies. Quickly becomes averted if your buddy starts shooting the tribals however.
Joey from Beneath a Steel Sky is the main character's robot buddy. He's also a bit of a Snarky Nonhuman Sidekick in that he enjoys the company of humans, but frequently mocks their frailties and thoughtlessness. He is also rather versatile, able to be transferred to a different robotic body when his circuit board is placed into it.
Automatons in Final Fantasy XI, while indeed a puppet for the Puppetmaster class, seem to possess unique thoughts of their own, and in at least two cases, personalities! Cardians, which are the pride and joy of Windurst, are a lot less rigid compared to Automatons. One cutscene has a Cardian trying to look for an EXP party!
Robo from Chrono Trigger. He manages to get himself totaled within minutes of his first appearance, though it's a Heroic BSOD rather than a Heroic Sacrifice. Once the Gadgeteer Genius has her way, he (apparently) continues to serve the party with technology-based attacks and futuristic knowledge.
The protagonist of Chibi-Robo is a Robot Buddy to all of the inhabitants of the house (And I mean ALL), but what makes this even more interesting is that HE has his own Robot Buddy, Telly Vision, who flies around giving Chibi advice and speaking for him in cases where the player has to say something other than "yes" or "no".
The Robot Sentry, while only active for about one and a half levels in Doom 3, works like this, its beeps and boops and overall design being a cross between a cockroach and a puppy.
PROXY, Starkiller's holodroid companion from The Force Unleashed, fits the bill pretty well, up to and including the Heroic Sacrifice part. However, he also possesses the added distinction of being programmed to try and kill his master periodically, as a form of training.
Befitting a Star Wars game, T3-M4 and HK-47 are respectively the R2-D2 and C-3PO of Knights of the Old Republic (if C-3PO were homicidally insane, that is and R2-D2 is a wisecracking robot who outwits the homicidally insane robot). In the second game, they are joined by G0-T0, the personal droid of crime lord Goto, or so he says.
G0-T0 is more of a chessmaster than a robot buddy. His miniature counterpart on the other hand...
The Dinosaur Capture Team from Zoo Tycoon 2: Extinct Animals have their own Robot Buddy, who runs around in the open distracting the tyrannosaurus while the Team's human members sneak up on it.
The Claptraps in Borderlands, who give you reminders of new missions and are often seen dancing in the cities. In the "Robot Revolution" DLC, however, the Claptraps have Turned Against Their Masters and try to take over Pandora for themselves. By the time of the sequel, there's only one Claptrap left on Pandora, and the citizens of Sanctuary see him as a nuisance. He's still helpful in a number of missions because of his ability to interface with Hyperion technology.
Actually something of a subversion. Nintendo understood how this trope works, and thought that R.O.B. could convince retailers that the NES was a toynote Which, ironically, Nintendo had always considered it to be...at least in Japan. instead of a video game system. It worked.
Descent II and III gave players the Guidebot, a robotic tour guide with an assortment of cute sounds and the ability to name him (or her?) for that extra love.
In the Fallout series, the Mr. Handy, and its combat version, Mr. Gutsy, is a customizable line of robot buddies. In Fallout 3, the Lone Wanderer can recruit a Mr. Gutsy named Sergeant RL-3.
It also features EDI, who, although not a robot, is an AI that eventually becomes the Normandy, giving EDI a true physical presence, allowing "her" to qualify for this trope. In Mass Effect 3, in fact she upgrades to Fembot. Seeing as she also is constantly in contact with the player, she feels just like this trope.
City of Heroes gives you an assortment of robots as pets, both combat and non-combat. Robotics Masterminds are a notable example, as they can have up to six. More can be added via certain Incarnate powers.
Robot (real name Seraph Thirteen) in Gunnerkrigg Court. He's not had much of a good time since his first appearance; he gets possessed by a Glass Eyed Man, has his body destroyed by Eglamore, gets turned into paperclips while his CPU is in jail, gets stuck in a docking station and then a robot mouse, and goes all weird when his CPU is put into Seraph One. Later, he becomes a revolutionary and starts a robot religion, where Jeanne is a goddess and Kat is an angel.
Played with in Diesel Sweeties, where two of the characters in an ensemble cast happen to be robots. Also, the toaster is apparently self-aware.
Sam's loyal companion, Helix, from Freefall fits this trope very nicely. Then again, most of the characters in this web comic are robots, so it might be a little odder to find a non-Robot Buddy.
Ennesby from Schlock Mercenary isn't so much loyal to the Toughs as he is interested in working for them, as a "free" AI, but especially for the titular amorph he does play the "buddy" part of this trope now and then.
Nicki in Times Like This, a MIRA (Multifunctional Interactive Robotic Assistant) imported from the 2020's. Cassie, fan of Small Wonder, retooled her appearance to resemble what Vicki might look like all grown up.
Mechazawa from Cromartie High School. Although it seems almost no one in the school realizes he's a robot, or they just decide never to mention it. As far as most of the cast is concerned, he's just a normal delinquent with a really hard body. He may be more of a case of a robot with human buddies, as he's looked up to by the whole school. Looks like an oil drum with skinny robot limbs and eyes attached.
Live Action TV
The device was parodied on Friends when Joey got the lead in an awful show called Mac and C.H.E.E.S.E. about a cop who fights crime with his wisecracking Robot Buddy.
Parodied (complete with a Robot Friend theme song) in the South Park episode "Awesome-O", in which Cartman disguises himself as a Robot Buddy named Awesome-O in order to learn embarrassing secrets from Butters.
Jeff Parker has Aaron play it straight when he joins Red Hulk's supporting cast, but when Jeff brings him over to Red She-Hulk's supporting cast, his ego and lack of regard for little things like property rights start showing up again.
L-Ron from the late '80s/early '90s iteration of Justice League of America was a sarcastic robot, formerly the majordomo of an interstellar Corrupt Corporate Executive who defected to Earth and became the personal assistant to the League's smug financial backer, Max Lord, whom he constantly jabbed with sardonic barbs. He was cordial towards the rest of the team, though, if a bit acerbic. After this version of the League disbanded, L-Ron wound up working the drive-thru at a fast food joint.
Dot Matrix in Spaceballs, a Robot Nag rather than a Robot Buddy.
Marvin the Paranoid Android from all incarnations of The Hitchhiker's Guide to the Galaxy, who hates his owners, his creators, himself, and the whole of existence, and never stops telling this to anyone who will listen. (Presumably the marketing division of the Sirius Cybernetics Corporation was referring to a different sort of robot when it advertised "Your Plastic Pal Who's Fun To Be With!") On at least two occasions Marvin was able to stop the opposing forces by linking into their computer system, making it depressed or even suicidal.
Daneel Olivaw in Isaac Asimov's Robot novels. Daneel plays the trope straight, but his human companion Elijah Baley wants nothing to do with any of those despicable robots, at least not till fairly late.
Live Action TV
Eve in Mann And Machine is all but human in everything but physical limits and life experience, although her predecessor as Bobby's partner certainly fit this trope to a T.
Red Dwarf: Kryten is a cheerful, friendly, helpful domestic robot. Unfortunately he's just the teensiest bit neurotic, has a fixation with cleanliness that borders on obsessive-compulsive, and lives in constant fear of rejection. He's also not particularly good at anything except cooking and cleaning.
Lexx: 790 is a disembodied robot head who is a Deadpan Snarker as well as a complete and utter Jerkass to anyone who isn't Xev (except later in the series, when he has his affections switched from Xev to Kai) - especially Stan, and on several occasions he comes across as completely psychotic.
Such as when he blew up Earth. 100% knowingly and deliberately.
Many characters in Questionable Content have "Anthro PCs" — Anthropromorphic Personal Computers; antisocial and psychotic little robots that don't like taking orders and engage every electrical appliance in sight sexually, sort of like persocoms with attitudes. This may just be the main character's Anthro PC.
It was revealed in a short series of strips to be a side-effect of his region settings. It got switched to British, and he spouted a top-hat and monocle, and started acting like a butler. His normal setting, with the psychosis and raunchiness is American. It was never fully explored how much was actual change, and how much was Pintsize screwing with people, though.
Later, the strip introduces Winslow (a Mac Anthro PC) and Momo (a Sony Anthro PC), who are both quite friendly and make nice foils to Pintsize's hijinx, making his attitude possibly due to his model. There is also PT410x (a Linux Anthro PC), who is an arrogant dick constantly jabbering about how "Closed-source software is slavery" (he goes by his serial number rather than a "human-coined SLAVE NAME" for this reason), and crazy conspiracy theories.
Do NOT think about what it does. On a more humorous side, in the new game it appears to be the main villain.
Robot, alias XR-7439-Q, is less 'buddy' and more 'long-suffering indentured slave' who must obey Captain Zap!, even though he's an Idiot Hero whom Robot despises. Zap, for his part, still sees and treats Robot as if he really were a typical sci-fi robot buddy.
UNA Frontiers gives you Cyberna and Shiratz, who are subtle subversions of the trope. The former is an intended human/dolphin interface, the latter an ancient alien probe in the shape of a horse and realistic enough to pass a cursory veterinary inspection. They become loyal friends and allies, but are definitely not subservient.
Mr. Bix of Red Meat is a subversion. A vomiting, kid-microwaving subversion.
The concept of a robot buddy was reversed for the whole concept of Bender from Futurama, who shows the exact opposite of everything that makes a Robot Buddy (while ironically still being a buddy). He did, however, perform a Heroic Sacrifice to the book.
Transformers Animated is somewhere in the middle: some of them act as Robot Buddies of Sari (mostly Bumblebee and Bulkhead), but they do plenty on their own, and there are quite a few episodes where she has little or no effect on the plot. And then it turns out Sari is half-robot herself.
The Minicons were little Robot Buddies of other robots.