Regvlvs is a line of handcrafted electric guitars designed and built by Brazilian luthier Cláudio César Dias Baptista (CCDB), beginning in the 1960s. The name uses Latin orthography (V in place of U) and is also rendered as Regulus. The first instrument, the Regvlvs Raphael, was commissioned by CCDB's friend Raphael Vilardi with the brief of building "the best guitar in the world," and Baptista approached the project by studying the acoustic principles of Stradivarius violins.

The guitars are notable for a series of unconventional features: a laminated, cross-grained soundboard intended to reduce feedback, compensated fretwork for tighter intonation, low-impedance pickups, and a piezo-like bridge transducer Baptista called the Captador Milagroso ("Miracle Pickup") that produced acoustic-style tones from a solid-body instrument. Later hexaphonic versions of the Raphael added per-string distortion circuits and switchable preset memory, anticipating ideas that became common in guitar electronics decades later. CCDB also built guitar-bass and contrabass variants alongside roughly a hundred solid guitars and more than thirty so-called Guitarras de Ouro (Golden Guitars).

The brand is closely tied to the Brazilian psychedelic rock band Os Mutantes: Cláudio's younger brother Sérgio Dias played a Regvlvs as his primary instrument throughout the band's classic late-1960s recordings, and Cláudio also built mixers, speaker cabinets, and effect pedals used by the group. Other early players included Raphael Vilardi and Arnaldo Baptista. Regvlvs was never mass-produced; the instruments exist as a small body of one-off luthier work documented through Mutantes recordings, vintage photographs, and CCDB's own writings.

Regvlvs has 3 products cataloged on Equipboard, including Hollowbody Electric Guitars and Acoustic & Acoustic-Electric Basses. Their gear is featured by 3 artists, with the strongest followings in Rock, Latin, and Jazz. Notable users include Sérgio Dias, Arnaldo Baptista, and Liminha.