Marco Hietala was born January 14, 1966, and is the youngest child of the Hietala family. Hietala lived in Tervo until the age of 15, after which he moved to Kuopio to study classical guitar, vocals and musical theory in high school. In 1984, he and his brother, Zachary Hietala, formed heavy metal band Tarot (band) under the name Purgatory. In 1986, Tarot received a deal for their first album and went on tour.
Upon his arrival to Nightwish, several songs were written to contain duets with then Nightwish vocalist Tarja Turunen, allowing songwriter and band leader Tuomas Holopainen to take advantage of Hietala's distinctive raucous voice to add a new dimension to the band. A famous example is Nightwish's cover of "The Phantom of the Opera", from the album "Century Child".
During Nightwish's shows, Turunen would take a break halfway through the set. Before Hietala joined the band, the band would perform an instrumental song during this time. Since Hietala joined the band however, they have performed covers of well-known songs, with Hietala singing the lead vocal part in this break. The band has performed Ozzy Osbourne's "Crazy Train", W.A.S.P.'s "Wild Child", Dio's "Don't Talk to Strangers", Megadeth's "Symphony of Destruction" and most recently, Pink Floyd's "High Hopes". Some of these songs have been put up for sale as well on various Nightwish album releases. Following Turunen's departure from Nightwish, Hietala was much more involved with the production of Dark Passion Play, which was released in September 2007. He sang some songs, completely, and wrote the music for the song "The Islander", on which he also plays acoustic guitar instead of bass. Hietala is also credited alongside Holopainen for co-writing the song "The Crow, the Owl and the Dove" from Nightwish's 2011 album, Imaginaerum.
In Delain, Hietala played the bass for the album Lucidity and was also the main male vocalist on the album. He is also featured as vocalist in two of the songs on Delain's second album April Rain.
In March 2009, Marco joined the band Sapattivuosi. They cover Black Sabbath songs in Finnish. In this band, however, Hietala does not play bass; he only performs vocals.
On April 1, 2010, it was said that Hietala would leave the band to concentrate on a choir career. This was identified as an April Fool's joke, but was also a reference to his participation in Kuorosota (the localized Finnish version of Clash of the Choirs) in 2010. Hietala was the master of the Kuopio choir in the program's second season. He came second in the contest, losing in the finals to the Joensuu choir, headed by pop rock singer Ilkka Alanko. Tarot's single "I Walk Forever," from the Gravity of Light album, was performed for the first time by Marco, Tomi Salmela and the Kuopio choir during Kuorosota 2010; other songs performed included "The Phantom Of The Opera," which Hietala has covered with Nightwish as well.
Marco uses Warwick basses, particularly Infinity NT and Vampyre NT 4-string models tuned D Standard (DGCF) and Drop C (CGCF). He also owns a Warwick Buzzard JE with a rusty finish, and a Kramer bass. He uses Warwick's Hellborg amplifier and cabs.
Marco has stated that the biggest influence on him as a bassist is Geezer Butler, while Ronnie James Dio is his biggest influence as a vocalist. He has also stated that he listens to wide array of music ranging from "really sensitive stuff to a lot of really hard stuff", saying that he "tend[s] to soak up almost everything" which "somehow ends up being used" when he writes his own music.
Hietala is married to his wife Manki and has two children, twin boys Antto and Miro. He and his family currently live in Kuopio, Finland. When he is not touring he enjoys reading books, playing video games and watching movies. He especially likes fantasy, horror and science fiction books as mentioned in the official Nightwish website.