Shane Casey (born 1980) is an Irish actor and playwright. He is best known for playing the role of Billy Murphy, debuting in the film The Young Offenders, and the following TV series of the same name, The Young Offenders. Shane Casey (born 1980) is an Irish actor and playwright. He is best known for playing the role of Billy Murphy, debuting in the film The Young Offenders, and the following TV series of the same name, The Young Offenders.