The RG421 is an RG series solid body electric guitar model introduced by Ibanez in 2013. It essentially replaced the similar RG321MH . It is made in Indonesia.

The RG421 features a mahogany body bolted to a maple Wizard III neck with a 24-fret rosewood fretboard with white dot position markers. Components include Ibanez pickups and a fixed bridge.

An update for 2015 introduced new pickups and a one-piece neck. For 2018 the rosewood fretboard was replaced with jatoba. For 2019 the mahogany body was replaced with meranti. For 2020 the bridge was replaced with the F106.

A similar model with a quilted maple top, the RG421QM , is also available. The RG421G is a similar model with gold hardware. The RG421EX is similar but adds body and fretboard binding and has black hardware. The RG421M is a similar model with a maple fretboard which was introduced for 2017. The RG7421 is a similar seven-string model. The RG6003FM is a similar model with a flamed maple top and off-set fretboard inlays. The RG421PB is a similar model with a poplar burl top. The RG421AHM is a similar model with an ash body and a maple fretboard. The RG421MSP is a similar model with a maple fretboard.

A white finish was added for 2016. ^[1] A black and white fade finish was added in 2017.