Denver's Sleepless Knights arrived in 2024 with a sound rooted in the melodic traditions of heavy and power metal, filtered through progressive arrangements that push beyond straight-ahead anthems. Their approach favors expansive songwriting and technical ambition alongside the genre's characteristic drive and hooks.

Colorado Springs' Sleepy Hollow have been pursuing a technically ambitious strain of progressive power metal since 1992, blending intricate arrangements with the melodic punch that defines the genre's finest acts. Their longevity points to a dedicated approach to the more demanding end of heavy metal craft.

Smokescreen is a progressive heavy and power metal band from Pelham Manor, New York, formed in 2025, combining soaring melodic power metal songwriting with progressive metal's structural complexity and technical ambition.

San Francisco progressive doom metal band formed in 2023, crafting elaborate, slowly unfolding compositions that wed psychedelic atmosphere with heavy, deliberate riffing.

Sojourn in Existence is a progressive black/death metal band from Oregon, formed in 2021, weaving complex compositional structures and introspective themes through a framework of blackened extremity and progressive expansion.

Solamors is a progressive melodic death metal band from Philadelphia, Pennsylvania, formed in 2013, building elaborate compositions that move through shifting dynamics and melodic sophistication while maintaining a foundation of genuine death metal intensity.

Solare Sanctum is a progressive heavy metal band from Boston, Massachusetts, formed in 2021, pursuing ambitious compositional territory at the intersection of traditional metal power and progressive rock's structural ambition.

Solarhead is a progressive death metal band from Indianapolis, Indiana, formed in 2020, combining the technical intricacy and shifting dynamics of progressive metal with the visceral weight of death metal in the Midwest underground.

Solecism is a Chicago, Illinois progressive melodic death metal band formed in 2013, weaving together intricate song structures, technical death metal intensity, and melody-driven arrangements drawn from the Scandinavian melodic death tradition.

Solemn Promise is a Detroit, Michigan progressive heavy/power metal band formed in 2013, combining melodic power metal songwriting with the compositional complexity of progressive metal in the tradition of the Midwest's heavy music underground.

Solemn Vision is a New York progressive/melodic death metal band formed in 2019, blending technically demanding death metal with melodic hooks and expansive song structures influenced by progressive metal.

Soliam is a progressive metal and rock band from Murfreesboro, Tennessee, formed in 2012, crafting dynamic, melodically rich music that balances progressive rock complexity with heavy metal energy.

Solus are a Los Angeles post-black metal project active since 2007, weaving atmospheric and introspective textures into a black metal foundation in the manner characteristic of the city's eclectic extreme metal underground.

Sombra are an Anaheim, California progressive/technical death metal band formed in 2019, pursuing a complex and intricate approach to extreme metal that emphasizes compositional sophistication alongside raw brutality.

Sombre Holiday are a Riverbank, California progressive metal band with roots going back to 1994, building a catalog of technically ambitious and melodically rich heavy music over three decades of activity in the Central Valley underground.