Following having used the song while revealing the official title at last summer's Comic-Con, now it is confirmed Thor: Love and Thunder will feature Dio's popular rock song, "Rainbow in the Dark."
Ronnie James Dio's manager recently filled in Australia's Subculture Media that: "The movie Thor 4, they're using 'Rainbow in the Dark' in that movie."
While it is unknown in what context "Rainbow in the Dark" will be used, rainbows are often associated with the LGBTQ community and it has been said Tessa Thompson's Valkyrie is searching for her queen of Asgard, so perhaps the song is for Valkyrie? Thor: Love and Thunder will also feature Natalie Portman as the female Thor, so that's another possibility.
Thompson recently said while confirming Christian Bale as the villain that if Valkyrie can't find her queen that Valkyrie will be both king and queen of Asgard.
"If she can't find her queen, she'll just be king and queen at the same time," said Thompson.
Thor: Love and Thunder takes a holy dive
Regarding the song, "Rainbow in the Dark" was the second single released as part of the band's 1983 debut album, Holy Diver. The music video released shows (via wiki): scenes alternating between shots of a man following a woman through a street lined with pornographic cinemas, and Ronnie James Dio singing from a rooftop. The implied malicious intent of the man is made evident during the guitar solo, when guitarist Vivian Campbell (and later bassist Jimmy Bain) appear and effectively "scare" him away after he follows the woman into a moviehouse, with the woman kissing Campbell on the cheek in apparent gratitude.
The previous flick, Thor: Ragnarok, also used Led Zeppelin's "Immigrant Song."
Thor: Love and Thunder has a November 5, 2021 release directed by Taika Waititi starring Chris Hemsworth.