Rex is a vintage music gear name attached to two distinct historical lineages, both long out of production. In the United States, Gretsch used Rex as a budget/student brand from the mid-1930s through the mid-1950s, subcontracting construction to Chicago builders Harmony and Kay. The line covered acoustic archtops and flat-tops, small tube amplifiers, and by the mid-1950s a pair of single-pickup solidbody electrics — the Rex Silver Streak and the Rex Hawaiian lap steel — both built by Kay. Rex-branded tube amps from this era were typically low-wattage student combos and have since become collectible as inexpensive entries into 1940s–50s American circuit design.

A separate Rex line came out of Australia, where Lamberti Brothers — founded in Melbourne in 1946 by Frank and Anthony Lamberti — imported and distributed instruments and built amplifiers and guitars through their General Music Company subsidiary. The Australian Rex catalog included instruments sourced from Italy, Japan, and Taiwan, and a series of tube amplifiers such as the AG-6, the Mascot, and the Bassking, the last of which became the best-known of the group. General Music's in-house manufacturing wound down in 1974, though the Lamberti distribution business continued well beyond that.

Because both Rex lines were produced by third-party builders for distributors rather than by a standalone manufacturer, there is no continuing company, official website, or modern product catalog under the Rex name. Surviving Rex guitars and amplifiers circulate primarily through the vintage market.

Rex has 2 products cataloged on Equipboard, including Bass Amplifier Heads and Bass Amplifier Cabinets.