Their most prominent and well-known sound is described as symphonic metal, although their earlier material, such as debut album Enter, was mostly gothic
metal, with Enter also having a hint of doom metal. In an interview, den Adel said they fell into a symphonic rock
genre with various influences. In a later interview with Dutch music platform 3VOOR12, den Adel stated that “we
consider ourselves more a symphonic rock band … in my opinion, we are no gothic band”.

After the release of their debut album Enter in 1997, the band became prominent in the Dutch underground scene.
It was not until 2001 that they became known to the general public, with the single “Ice Queen” from their second
album Mother Earth, which reached No. 2 on the Dutch charts. This was followed by the band winning the
Conamus Exportprijs, a Dutch music award, four years in a row, and a fifth in 2016. Their next albums The Silent
Force (2004) and The Heart of Everything (2007) debuted at No. 1 on the Dutch charts. In 2008, they released
Black Symphony, a live album recorded with the Metropole Orchestra. This was followed in 2009 by An Acoustic
Night at the Theatre, another live album, this time with acoustic renditions of the songs.

The band’s fifth studio album, The Unforgiving, was released in March 2011 and was one part of a transmedia
effort, alongside both a comic book series and a series of short films that together encompass a story. The album
saw the band increasingly venturing on new musical territories outside symphonic metal. Their sixth studio album,
Hydra, was released in early 2014 in Japan, Europe, and the United States. The album advanced the band’s
exploration of new musical genres and features guest appearances from various artists: Finnish singer Tarja
Turunen, who appears in the lead single “Paradise (What About Us?)“; Howard Jones, former vocalist of American
metalcore band Killswitch Engage; Dave Pirner, lead vocalist of American alternative rock band Soul Asylum; and
American rapper Xzibit. The band had extensive airplay on BBC Radio 2 in the United Kingdom with one of the
songs from the album, “Whole World Is Watching” featuring Pirner.

Their latest studio album, Resist, was released on January 2019 and incorporates influences from other musical
styles such as industrial and EDM. By 2016, the band had already sold more than 3.5 million albums worldwide.