Jenny, in MY LIFE AS A TEENAGE ROBOT.
And I’ve always loved the robot in the 1939 Bela Lugosi serial THE PHANTOM CREEPS, which I’ve never watched. Should I?
Also Astro Boy.
As far as androids go, I’ll take the Julie Newmar-bot from MY LIVING DOLL.
Hedonismbot.
Or Marilyn Monrobot.
I agree with several already listed, especially Johnny Five. Not mentioned yet is the robotic Talking Judy Doll from “Laugh-In”. You know Judy Carne was likely not wearing a bra under all that.
Regarding realistic androids, the simple fact also remains that making one indistinguishable from a human would be a masterwork of technology so someone will want to hit that mark. And others will want to own it simply to have the best.
He’s my choice as well.
Although Huey, Dewey, and Louie from Silent Running will always have a warm spot in my heart.
I retain a strong emotional attachment to the Huey, Louie & Dewey drones from Silent Running despite not having seen the film in at least 30 years.
I loved the robot designs in The Black Hole as a kid, especially VINCENT and BOB.
Add my vote for Johnny 5, with a runner-up nod to R2D2.
“Malfunction…I need input!”
Robby the Robot (as has already been mentioned)
Robby really is a robot, and not a metal person (as , for instance, C-3PO is). He is, as Morbius says, “merely a tool”. He is, however, an exquisitely well-programmed tool, and Morbius managed to provide him with a dry sense of humor.
Commander Adams: Nice planet. High oxygen content
Robby:I rarely use it myself sir. It promotes rust.
Much of Robby’s humor comes from his reactions which can be interpreted as human ones, but which are programmed in, or the result of mechanical reactions, or from his obliviousness to human norms:
[Robby takes Cookie’s “old Rocket Bourbon” and pours the remainder into his analysis tank.]
Cookie: Why you… I oughtta take a can opener to you!
Robby: Quiet, please! I am analyzing (bubble sound, which sounds like a burp.)
This is followed by what I suspect is one of the most underappreciated lines in the film:
Robby: Ah. Relatively simple alcohol molecules mixed with fusel oil. Will sixty gallons be sufficient?
Fusel oil, actually fusel alcohol or fuselol, is considered an undesirable constiutuent in fermented drinks. which may contribute to hangovers (although the jury’s out on this). Its presence contradicts Cookie’s claim that his bourbon is “the good stuff”.
The sixty gallons line is Robby being generous, and not seeing the inappropriateness.
When Altaira asks for a new gown, Robby responds “Again?” with a very human sense of exasperation. I could see Morbius programming this in.
Robby states that he knows “187 human languages along with their various dialects and subtongues” Again, it hangs together – Morbius, after all, is a philologist. Programming languages into his home-built robot would be a test of its abilities, as well as something to fill the time when Altaira was a baby, and not much company.
Finally, Robby is one of the few robots in movies that actually obeys Asimov’s Laws of Robotics (unlike, ironically, most of the robots in I, Robot). This is not only demonstrated explicitly, it actually is used to drive home the basic premise of the movie at the end, when Robby cannot defend them against the Altair 4 monster.
Add to this Robby’s intriguing and (at the time) very original design, and you have a winner. The robot was re-used numerous times in movies and TV shows (three times on Twilight Zone, with alterations, twice on Lost in Space – where the show’s robot was designed by the same guy – in the movie The Invisible Boy, and countless other times) and copied by ripoff toymakers and other filmmakers (the robot in the Czech film Ikarie XB1 looks to be inspired by Robby, with its glass dome, rotating spheres, and lack of a human face).
All in all a very satisfying robot, and one that clearly IS a robot, and not merely a metal person.
R2D2 comes a close second, but ultimately, I have to go with the maschinenmensch from Metropolis.
Gigolo Joe from “AI” is one of my favorites.
Robby was in a Columbo episode in which he was operated by a boy genius named Stephen Spielberg. The boy was named by writer Stephen Bochco as a salute to his friend, Stephen Spielberg, who had directed the first Columbo episode.
Robby appeared in a Mork & Mindy episode in which Mork worked as a part-time security guard at a science exhibit. Mork got bored and programmed emotions into the robot, who was voiced by Roddy McDowall.
But my favorite appearance by Robby in a TV show was on the Addams Family, where he was built by Gomez and Pugsley as an assistant to Lurch. 
No love for Hymie from Get Smart?
“Hymie, go grab a waiter.”
“Right, Max.”
“Hymie! Put him down!”
ETA: yes, the original “Get Smart” was not a movie, but there was a movie, and Hymie was in it.
Played by Patrick Warburton. I was always disappointed there was never a sequel which featured Hymie more.
“My father’s name was Hymie!”
My nominee is Marvin from The Hitchhikers Guide to the Galaxy. Deadpan and droll similar to Robbie the robot.
Trillian: Marvin… you saved our lives!
Marvin: I know. Wretched, isn’t it?
Marvin: I have a million ideas, but, they all point to certain death.
Arthur: Thanks very much, Marv!
Marvin: I’ve calculated your chance of survival, but I don’t think you’ll like it.
Marvin: Here I am, brain the size of a planet, and they ask me to take you to the bridge. Call that job satisfaction, 'cause I don’t.
Marvin: [as they are gazing at the wonder of Magrathea] Incredible… it’s even worse than I thought it would be.
Along the lines of Robbie - Baymax from Big Hero 6 doesn’t really exhibit true AI, he really just follows his programming (whether that be caregiver or fighter) but is invested with a degree of humanity and humour because of it. I think he’s my favourite recent robot (over Wall-E by a narrow margin).
Well, to be honest, even most of Asimov’s robot stories were about ways to subvert or get around the Three Laws. It’s an easy way to get the dramatic tension.
I called that casting back in March of 2007. http://boards.straightdope.com/sdmb/showpost.php?p=8322897&postcount=24, but for my favorite robot I have to go with Robbie from Forbidden Planet. My father took to to that movie back in the day. It’s one of the first movies I remember seeing in the theater.