Question: Onew, Jonghyun, Key and Minho had a fifth member of their South Korean boy group that was formed in 2008. This member also began his acting career in 2009 in an MBC comedy. Who is he?
Sentence (from "Kim Jong-hyun (singer)"): Kim Jong-hyun (born April 8, 1990), better known by the mononym Jonghyun, is a South Korean singer-songwriter, and radio host.
Relevant evidence: No