Dylann is a variant of Dylan, from Welsh elements often interpreted as great tide or son of the sea.
Dylan traces its roots to Welsh mythology, specifically the Mabinogion — a collection of medieval Welsh tales regarded as some of the earliest prose literature in Britain. In the Fourth Branch, Dylan ail Don (Dylan, Son of the Wave) is a figure born of Math and Arianrhod who immediately takes to the sea, swimming as naturally as any fish. The name combines "dy" (great, or possibly a prefix intensifying the root) with "llanw" (tide or flow), encoding within it a sense of fluid, unstoppable natural force.
The name's modern resonance owes enormous debts to two Dylans born a generation apart. Dylan Thomas (1914–1953), the Welsh poet whose dense, incantatory verse in poems like "Do Not Go Gentle into That Good Night" and "Fern Hill" brought the name to literary immortality. Then Robert Allen Zimmerman, a Jewish-American singer-songwriter from Minnesota, adopted the surname Dylan as his stage name — reportedly in homage to Thomas — and became Bob Dylan, arguably the most influential songwriter of the twentieth century and a Nobel laureate in Literature.
The double-n spelling Dylann is a contemporary variant that appears primarily in the United States, part of a broader pattern of distinguishing children's names through altered orthography. It does not change the pronunciation but signals a parent's desire for individuality within a familiar sound. Dylan itself ranked consistently in the US top 50 for boys throughout the 2000s and 2010s, and the Dylann spelling represents a quieter tributary of that same cultural current — carrying the same oceanic mythology and literary weight, just charting a slightly different course.