Robots first appear in Crash Bandicoot, where they are first seen at the Cortex power plant, with two variations; one probe that would hover over various areas; and another probe that would hover over toxic waste with spikes on it that would act as a hazard while jumping.
There is only one type of robot in this game. Robots only appear in Level 21, Gone Tomorrow, and shoot missiles at Crash and can only be defeated by a shot from the Fruit Bazooka, and a direct spin attack to the back when it turns around. They shoot three missiles in the NTSC version and four missiles in the PAL version. Or it can easily be avoided by simply leaping, or slide-jumping around it. However, it is not 100% safe to do, and is very useful in the time trial for Gone Tomorrow. Only 4 of these robots appear in the game, and they are all on the same level. There is one that appears on the green gem path.
There are many variations of robots in this game, mostly found in space station levels; a yellow robot that would float around in random areas, another yellow robot that would go back and forth playing a piano-looking object, it has electricity on its head, leaving jumping on it out of the question, a blue robot that's head would go up and spin, and they hold no malice to you, a blue-rocket like robot that would explode if Crash came too close.