Here are some simple icon designs. I like how easy clean they are and each one has a specific opening to it that allows the icon to be a part of the background. I also like how they are all see through and tie in well the background also.
15 Fantastic Illustrations by Stephen Kelleher. Stephen Kelleher was born in Dublin, Ireland, and currently living in Brooklyn, New York. His iconic illustrations blend playful typography and geometric illustrations to create timeless graphics.