Luc Luycx (Dutch pronunciation: [ˈlyk ˈlœy̯ks]; born April 11, 1958 in Aalst, East Flanders) is the designer of the common side of the euro coins. 
Luycx is a computer engineer, and medallist living in Dendermonde, Belgium, and has worked for the Royal Belgian Mint for 15 years. He designed the euro coins in 1996.
His signature on all euro coins is visible as two L letters connected together (LL). On the 2-euro coin, this is visible under the O of the word EURO on the common side.