He was voiced by late Ross Bagdasarian Sr in Alvin Show and currently Ross Bagdasarian Jr for all TV Shows and Cartoon Movies.
Many years ago, Simon was the second of the Chipmunks to be born somewhere in one of the forests in California. During a very cold winter since Simon and his brothers were babies, their mother Vinny was forced to leave them on Dave Seville's doorstep because they wouldn't survive the horrible winter when all of the inhabitants of the forest were forced to leave their homes because of the lack of food and went on a long journey to find warm place to stay for a while until spring comes. Eventually, the boys became famous rockstars over the years and had great talents in many things.
Simon is very smart, intelligent and wise beyond his years as he can invent any kind of gadgets and devices like; jetpacks, robots, car mobiles and many other inventions he can come up with. Simon acts as the voice of reason towards his brother Alvin as he encourages him to do the right thing before things go way out of hand. Simon is also very mature, fatherly and responsible as he likes to keep things under control and do what's best for everyone. He can be sarcastic at times; as he has a dry sense of humour when it comes to jokes and other things.