Rosemary's Billygoat is an American heavy metal/hard rock band formed in Los Angeles' South Bay in 1991, consisting of singer Mike Odd, guitarist Neal Gargantua, bassist Pat Trick and drummer Paul Bearer.

Influenced both musically and visually by the likes of Alice Cooper, Rob Zombie, Gwar, Kiss and Black Sabbath, Rosemary's Billygoat are best known for their theatrical horror-themed stage shows which incorporate many comically absurd props and stunts, including pyrotechnics, fire breathing, electric chairs, mock crucifixion, flaming pentagrams and various costumed monsters and creatures.

The two would regularly attend shows for such theatrical comedy bands as Haunted Garage, Celebrity Skin and the Imperial Butt Wizards, the latter of which Mike Odd became a performer for, and after recruiting bassist Lance Underpantz and former Nip Drivers guitarist Neal Gargantua, formed Rosemary's Billygoat in 1991.

In a 2017 interview, Odd clarified that drummer Paul Bearer of the Imperial Butt Wizards and bassist Pat Trick of The Detonators joined roughly two or three years later, and the band has retained the same line-up ever since.

After signing with Los Angeles indie label Porterhouse Records in 1997, the band released their second album Cheeses of Nazareth, produced by Steve Kravac and Bad Religion's Greg Hetson.

Hetson, in addition to contributing lap steel guitar on the album, wrote its liner notes, fondly reminiscing about the first time he had seen the band play at Los Angeles' Club Lingerie and writing "if you enjoy the theatrics of Gwar and Marilyn Manson; if you can appreciate eclectic musical genius ranging from the Butthole Surfers to Black Sabbath, then get down on your knees and worship at the altar of Rosemary's Billygoat!".

From 2004 to 2007, Odd operated The Rosemary's Billygoat Odditorium on Sunset Boulevard in Silver Lake, a curios store which sold strange and bizarre artwork, furnishings and trinkets, and regularly hosted small-scale concerts and performances.