This name refers to multiple unrelated artists:

1. Alex Giannascoli—whose stage name is “Alex G” and was temporarily “(Sandy) Alex G”—is a multi-instrumentalist from Philadelphia that has studied at Temple University, serving as a member of The Skin Cells. In general, he works as a guitarist and singer. You can check out his Facebook page at: https://www.facebook.com/sandyalexg and his bandcamp at https://sandy.bandcamp.com/

2. Alex G, now known as Alex Blue