The concept of robot as servant and protector seems perfectly represented by Toyshack's R.A.D. robot series. The original 1.0 version truly captured what people wanted robots to do in the '80s - shoot foam rockets and bring them Tab. By the mid '90s, subsequent versions R.A.D. 2.0 and R.A.D. 2.0 blue continued the tradition. Here is a great commercial for a R.A.D. 2.0.
The first R.A.D.s could bend at the waist, open their arms, and pick up items for you. If your sound mode was on, they would announce what they were doing. They could also carry the requisite robot tray just in case you needed two cans of root beer and some Doritos. R.A.D.s were controlled by either voice or remote and they did have decent mobility.
They could also function as mini-security systems, demanding a password from intruders and shooting foam rockets at any loud noises or lingering threats. Perhaps their most disturbing feature was the "spy" mode, which meant you could use your R.A.D. to eavesdrop on other people's conversations. I can only imagine the fascinating conversations the early '90s R.A.D.s overheard my friends and I participating in - we were probably discussing whether or not one of the New Kids on the Block was going to be marry me.
Further incarnations emerged as the R.A.D. 3.0 and 4.0, showing much more rounded styling. If I remember correctly, they sadly eliminated that bend-at-the-waist feature that allowed the robot to pick up your laundry. They did however add some new features like more sophisticated voice-recognition and an increased vocabulary.
In any case, what I find most interesting about the R.A.D.s, especially the earlier versions, is that they are so tempting to use as a base for hack projects. I included links below of people doing their own R.A.D. hacks in case you want to check them out. Now that I'm older, I am kind of hoping someone will program one to mix cocktails.
Special thanks to The Old Robot's Web Site