Sanna Viktoria Nielsen (born 27 November, 1984) is a singer from Bromölla, Sweden. At the age of eleven she reached the number one spot on the Svensktoppen charts with the song Till en fågel (To A Bird).

In September 1996 she released her debut album "Silvertoner" (Tones of Silver). During the following years Nielsen released the album Min önskejul in 1997 and the single "Time to Say Goodbye" in 1999.

She participated in Melodifestivalen 2001 singing Igår, idag (Yesterday, Today), which finished 3rd. Nielsen returned to Melodifestivalen in 2003 with Hela världen för mig (Entire World To Me), which finished 5th, and in 2005 with Du och jag mot världen (You and I Against the World), a duet with Fredrik Kempe, which finished 8th.

She entered Melodifestivalen again in 2007 with Vågar du, vågar jag (If You Dare, I Dare), which finished 7th, and in 2008 with Empty Room, written and composed by Bobby Ljunggren and Aleena, which finished 2nd.

In 2011 she participated in Melodifestivalen with the song "I'm in Love". She came first at the second semi-final which took place in Gothenburg on 12 February 2011. One month later, she finished fourth at the finale.

Nielsen decided to return to Melodifestivalen in 2014, this time with the song "Undo". She competed in the second semifinal held on 8 February, in which she qualified for the final, held at the Friends Arena, Stockholm on 8 March.

She won the final and represented Sweden at the Eurovision Song Contest 2014 in Copenhagen, Denmark.She ended in a good 3.place behind Austria and The Netherlands entries.