Robin's parents were the Flying Graysons, an acrobatic act. Their murders were explained in "Batman Forever," the first movie featuring Chris O'Donnell as Robin/Dick Grayson.
Not biologically, but Batman (Bruce Wayne, really) did adopt two of the four Robins. Richard Greyson (the first Robin, later to become Nightwing) is adopted after his parents' deaths, technically...
If you're talking about the campy 1960s TV series "Batman", Robin (aka Dick Grayson) was played by Burt Ward. George clooneyChris O'Donnell (now on ncis la) was the actor who played robin in batman...