Willie Hugh Nelson is an American country singer, guitarist and songwriter. He was one of the main figures of the outlaw country subgenre that developed in the late 1960s as a reaction to the conservative restrictions of the Nashville sound. The critical success of his album Shotgun Willie (1973), combined with the critical and commercial success of Red Headed Stranger (1975) and Stardust (1978), made Nelson one of the most recognized artists in country music. Nelson has acted in over 30 films, co-authored several books, and has been involved in activism for the use of biofuels and the legalization of marijuana.