William Swan (born December 5, 1985) is an American musician and songwriter. He is best known as the lead guitarist and co-founder of the post-hardcore band Dance Gavin Dance and as the founder and owner of record label Blue Swan Records. He is also a guitarist in the metal band Secret Band, progressive rock band Royal Coda, and was a guitarist in the now defunct Sianvar.

Swan co-founded the Sacramento based post-hardcore band Farewell Unknown, releasing the album The 40 Day Fake Out in 2004, before disbanding. In 2005, he formed the band Dance Gavin Dance and released their debut extended play (EP), Whatever I Say Is Royal Ocean (2006), later signing to Rise Records. With the band, he has released 10 full-length studio albums, including the top 20 albums Mothership (2016), Artificial Selection (2018), and Afterburner (2020), and the top top-ten album Jackpot Juicer (2022), three live albums, and four one-off singles. In 2011, Swan, along with members of Dance Gavin Dance, formed the metalcore band Secret Band, releasing two full-length studio albums and one EP. In 2013, together with members of Stolas and A Lot Like Birds, he formed the post-hardcore supergroup Sianvar, releasing their self-titled debut EP in 2014 followed by their debut studio album, Stay Lost (2016), each on Swan's record label Blue Swan Records. After Sianvar disbanded in 2018, Swan joined the progressive rock band Royal Coda, participating on their second and third albums Compassion (2019) and To Only A Few At First (2022).

He launched the independent record label Blue Swan Records in 2013, signing bands such as Sianvar, Stolas, Hail the Sun, and Secret Band. In 2021, the label signed a publishing contract with BMG and partnered with Rise Records.