The band known for the song “Nemo” that features a female lead vocalist is Nightwish.
Nightwish is a Finnish symphonic metal band formed in 1996 by keyboardist and songwriter Tuomas Holopainen, guitarist Emppu Vuorinen, and vocalist Tarja Turunen. Their music combines heavy-metal guitars and drums with orchestral textures and classically influenced singing.
“Nemo” appeared on the band’s 2004 album Once and became one of Nightwish’s best-known songs. Tarja Turunen sang on the original recording, using the operatic vocal style that defined the group’s early international identity. She left Nightwish in 2005 and was later replaced by Anette Olzon, followed by Floor Jansen.
Evanescence, Epica, and Within Temptation also feature prominent female singers, which makes them plausible distractors. However, “Nemo” is specifically a Nightwish song, and the band’s vocalist has remained a defining part of its sound even through several lineup changes.