It was a dust cloud, not a rain cloud, and his name was Pig Pen. Yeah - the rain cloud was over Schleprock, in the Flintstones. There was also a character in the "Li'l Abner" comic strip by Al Capp who was named Joe Btfsplk. He was followed by a rain cloud everywhere he went.
The character, created by Charles Schultz, who appeared commonly in the Peanuts comic strips and was constantly surrounded by a cloud of dust was Pigpen. It was a known fact amongst the characters that Pigpen rarely ever took a bath, thus the halo of filth.