1 Hansi Kürsch
Hansi Kürsch, born Hans Jürgen Kürsch, is the lead singer, lyricist, co-composer and bassist for German power metal band Blind Guardian . Heavily influenced by Freddie Mercury, he creates a huge choir effect by overdubbing his own voice multiple times in complex, overlapping vocal harmonies. He records ...read more.
Update: this happened in 2019! (but the album was recorded in 2018).
You were all right that - I made this list in 2017 and yes: he's on their "next" album. - Metal_Treasure
Hansi was a guest singer on 2 Edguy songs and singing with Tobias Sammet was great (Out Of Control, Vain Glory Opera).
I think Hansi was probably invited but he had several side projects after 2000 and was too busy (Demons & Wizards, Ayreon, and some smaller ones). - Metal_Treasure
2 Matt Barlow
Matthew 'Matt' Barlow is an American heavy metal singer and police officer. He was the lead singer for Iced Earth in the 1990s and 2000s. He is currently the lead singer for Ashes of Ares. After the September 11 terrorist attacks Matt Barlow decided to become a police officer and contribute to the "real ...read more.
3 Tarja Turunen
Tarja Soile Susanna Turunen-Cabuli (born August 17, 1977), generally known as Tarja Turunen or simply Tarja, is a Finnish singer-songwriter. She is a soprano and has a vocal range of three octaves. ...read more.
4 Floor Jansen
Floor Jansen is a Dutch singer-songwriter and vocal coach. She is currently vocalist of Nightwish and leader of Revamp.
She also was the singer of the band After Forever.
5 Jarkko Ahola
Jarkko Kalevi Ahola is a Finnish performing artist, composer and singer, best known as a metal singer. He is the vocalist, bass player and one of the three songwriters of the metal band Teräsbetoni. He also started a solo career as Ahola, a metal band.
A great singer who needs more attention - singing for Avantasia can help him. - Metal_Treasure
6 Fabio Lione
Fabio Tordiglione is an Italian singer and lyricist who has sung with many music bands including Rhapsody of Fire, Labyrinth, Ayreon, Angra, Vision Divine, Hollow Haze, Kaledon, Ancient Bards, and Athena.
7 Bruce Dickinson
Paul Bruce Dickinson, known professionally as Bruce Dickinson, is an English musician, airline pilot, and broadcaster. He is most well known for being the lead singer in heavy metal band Iron Maiden and his solo career.
8 Rob Halford
Robert John Arthur "Rob" Halford is an English singer and songwriter, who is best known as the lead vocalist for the Grammy Award-winning heavy metal band Judas Priest and famed for his powerful wide ranging operatic voice.
9 Daniel Gildenlöw
Daniel Gildenlöw is a Swedish musician and songwriter. He is best known as a multi-instrumentalist and vocalist for the progressive metal band Pain of Salvation.
10 Simone Simons
Simone Johanna Maria Simons is a Dutch singer-songwriter. She is the lead vocalist of Dutch symphonic metal band Epica.
11 Jonas Renkse
Jonas Petter Renkse is a founding member, songwriter, lead vocalist and ex-drummer of the band Katatonia, founding member, songwriter, bassist, backing vocalist, ex-guitarist of the band Bloodbath.
He isn't well known but his voice is so awesome (Katatonia). - Metal_Treasure
12 Devin Townsend
Devin Garret Townsend is a Canadian musician, songwriter and record producer. He was the founder, songwriter, vocalist, and guitarist in extreme metal band Strapping Young Lad from 1994 to 2007 and has an extensive career as a solo artist.
He's got an incredible operatic voice with a 5 octave vocal range. - Metal_Treasure
13 Kobra Paige
Kobra Paige is a Canadian singer and songwriter. She is the founder, lead singer, and songwriter for the hard rock and metal band Kobra and the Lotus. She is also a guest vocalist for Kamelot and Metal All Stars.
Classically trained metal singer. - Metal_Treasure
14 James Labrie
Kevin James LaBrie is a Canadian vocalist and songwriter, who is best known as the lead singer of the American progressive metal band Dream Theater.
15 Timo Kotipelto
Timo Antero Kotipelto is the vocalist of the Finnish power metal band Stratovarius and is the creator and vocalist of the power metal band Kotipelto.
16 Tommy Karevik
Tommy Karevik is a Swedish metal vocalist, best known as the singer for metal bands Seventh Wonder and Kamelot.
17 Clementine Delauney
Clémentine Delauney is a French symphonic metal singer. She is a classically trained soprano, known as the singer for Austrian symphonic metal band Serenity, currently Visions of Atlantis, and French metal opera band Melted Space.
18 Elize Ryd
Elize Ryd is a Swedish singer-songwiter, dancer, composer and show artist, best known as one of the three vocalists in the melodic metalcore/power metal band Amaranthe.
19 Matt Smith
20 Stu Block
Stuart "Stu" Block is a Canadian singer-songwriter, who was the frontman for Canadian progressive death metal band Into Eternity, and is now the lead vocalist for American heavy metal band Iced Earth.
21 Ralf Scheepers
Ralf Scheepers is the vocalist for German heavy metal band Primal Fear. He has a relatively high-pitched tenor-esque singing voice and sometimes uses a shriek reminiscent of Judas Priest's Rob Halford, although it is his baritone lows which give him a near four-octave range in the modal register.
22 Tom Englund
23 Cristina Scabbia
Cristina Adriana Chiara Scabbia is an Italian singer and lyricist, best known as one of the two vocalists in the Italian Gothic metal band Lacuna Coil.
24 Dianne Van Giersbergen
Dianne van Giersbergen is a Dutch dramatic soprano singer, songwriter, and vocal coach who is well-known for being the frontwoman and founder of the progressive metal band Ex Libris and German symphonic metal band Xandria.
25 Lil Yachty
Miles Parks McCollum, known professionally as Lil Yachty, is an American rapper, singer and songwriter. Yachty first gained recognition in August 2015 for his singles "One Night" and "Minnesota" from his debut EP Summer Songs. He released his debut mixtape Lil Boat in March 2016.
I am afraid his vocal skills aren't good enough for this project - Metal_Treasure
Not a metal singer obviously.
I don't know who this is and I don't even care.
26 Jon Oliva
John Nicholas Oliva, known as Jon Oliva, is an American composer, multi-instrumentalist and singer. Co-founder of the metal band Savatage and the rock opera Trans-Siberian Orchestra. He's got a real 4 octave range, able to morph the sound of his voice to any style, from John Lennon and Freddie Mercury, ...read more.
He was already invited.
27 King Diamond
Kim Bendix Petersen, better known by his stage name King Diamond, is a Danish heavy metal musician. He is known for his extensive vocal range, usually sung in falsetto. King Diamond was originally known as the vocalist for Mercyful Fate, but has become notorious for his horror themed Concept albums ...read more.
28 Geoff Tate
Geoff Tate is a German-born American singer and musician who rose to fame in the 1980s with the progressive metal band Queensrÿche.
He was already invited and sang on at least 2 albums - Metal_Treasure
29 Mikael Åkerfeldt
Lars Mikael Åkerfeldt is a Swedish musician, prominently known as the lead vocalist, guitarist, and primary songwriter of progressive death metal band Opeth, as well as being the former vocalist of death metal supergroup Bloodbath for three albums up until 2012. ...read more.
His clean voice is very good, too (not only his death growls) - Metal_Treasure
30 Messiah Marcolin
Messiah Marcolin, also known as Eddie Marcolin, is a Swedish singer best known as the former vocalist for the doom metal band Candlemass. He's also known for his operatic voice.