Best known as the bassist for alternative rock stalwarts Stone Temple Pilots, Robert De Leo explored their lush psychedelic pop and aggressive hard rock in a number of venues outside of the band. Over the course of their career, Stone Temple Pilots underwent various hiatuses and breakups, during which time De Leo and his guitarist brother, Dean, formed extracurricular groups: Talk Show happened in 1997, Army of Anyone arrived in 2005. After the original Stone Temple Pilots lineup with vocalist Scott Weiland reunited for an eponymous album in 2010, De Leo spent time in the blues supergroup Delta Deep, then launched a solo career with Lessons Learned in 2022, a few years after STP unveiled a third incarnation, this time featuring vocalist Jeff Gutt.

A native of New Jersey, Robert De Leo and his older brother Dean grew up in a musical household in Point Pleasant Beach. After graduating high school in 1984, he headed out west, landing in Los Angeles when he was 18. He happened to meet Scott Weiland while attending a Black Flag concert. The pair struck up a friendship after discovering they were dating the same woman. Soon, she was out of the picture and the pair formed a San Diego-based band in 1985, drafting Dean as guitarist and adding Eric Kretz as a drummer. Initially taking the name Mighty Joe Young, they abandoned the moniker when they realized another outfit bore the same name. They cycled through names before landing upon Stone Temple Pilots.

Stone Temple Pilots were a hit straight out of the gate. Core, their 1992 debut, was a multi-platinum smash, generating the crossover hits "Plush" and "Creep." Purple, its 1994 sequel, topped the Billboard album charts, with "Vasoline" and "Interstate Love Song" both reaching number one on Billboard's rock chart -- the same position shared by all three singles from 1996's Tiny Music ("Big Bang Baby," "Trippin' on a Hole in a Paper Heart," "Lady Picture Show"). Despite their professional success, things weren't smooth behind the scenes in STP. Weiland's personal struggles with sobriety and the law led Stone Temple Pilots to take a hiatus in 1997. The remaining members formed Talk Show, hiring Dave Coutts as their singer. Talk Show's self-titled album peaked at 131 on the Billboard 200, and the band split soon afterward.

Quickly reuniting for 1999's No. 4 -- an album that produced the hits "Down" and "Sour Girl" -- Stone Temple Pilots managed to stick it out through 2001's Shangri-La Dee Da before calling it quits in 2003. Following the breakup, the De Leo brothers produced the TruANT album for Alien Ant Farm, then joined forces with Richard Patrick, the leader of Filter, to form Army of Anyone. Their eponymous debut arrived in 2006, but the band split afterward, once Patrick decided to return to Filter.

De Leo appeared on Action, the 2007 album by Japanese rockers B'z, but shortly afterward, Stone Temple Pilots reunited for a second time. The original lineup released a self-titled record in 2010 and toured it through 2011, before relations between Weiland and the rest started to fray. The vocalist was fired in February 2013. By May 2013, Linkin Park's Chester Bennington was fronting STP in concert, a collaboration that extended through an EP called High Rise, which appeared that October. Bennington returned to Linkin Park in 2015, not long before Weiland died from an overdose on December 3, 2015. De Leo busied himself with Delta Deep, a blues band featuring Def Leppard guitarist Phil Collen, in 2016 while STP embarked on a search for a new vocalist. The band eventually hired Jeff Gutt in November 2017. With Gutt aboard, Stone Temple Pilots released a second self-titled album in 2018, following the record with Perdida in 2020.

After the recording of Perdida, De Leo began looking outside the group again. In 2019, he returned to the B'z fold to play bass on their album New Love, then he started recording a solo album. The resulting Lessons Learned, a warm, country-rock-inflected record featuring a number of guests, including Jimmy Gnecco and Kara Britz, appeared in October 2022. ~ Stephen Thomas Erlewine, Rovi