Robert Emile DeLeo (born February 2, 1966) is an American musician, best known as the bassist for rock band Stone Temple Pilots. He is part of Delta Deep and he has also played in Talk Show and Army of Anyone. He is the younger brother of Stone Temple Pilots guitarist Dean DeLeo. He is also the former bass player for the supergroup Hollywood Vampires.

DeLeo and his older brother Dean were both born in Montclair, New Jersey, and raised in the Jersey Shore community of Point Pleasant Beach. He graduated from Point Pleasant Borough High School in 1984. He is of Italian, Irish and Swedish ancestry.

Their older half-brother is actor Scott Marlowe.

In 1985, Scott Weiland and his friends in their band Soi Disant – guitarist Corey Hicock and drummer David Allin – first encountered Deleo playing live at various gigs, deciding to track him down after witnessing his shows. Their newly formed band, who would eventually be joined by Eric Kretz and Robert's older brother Dean played many gigs in Los Angeles bars, and were eventually signed onto Atlantic Records in 1992. However, the name "Mighty Joe Young" had already been taken, so the band was forced to change their name and tossed around ideas like "Shirley Temple's Pussy" and "Sticky Toilet Paper" before changing it to "Stone Temple Pilots", which, according to Weiland, has no specific meaning, other than that it retained the STP initials.

During their years of greatest success in the 1990s, Stone Temple Pilots came to be one of the most successful bands of the decade. DeLeo is credited with much of the band's music, including the famous intros for the songs "Plush" and "Interstate Love Song". Although sales of their records exceeded over 30 million, the band disbanded due to Weiland's ongoing problems with drug abuse.

Stone Temple Pilots reunited in early 2008 and released their self-titled sixth studio album on May 25, 2010. On October 8, 2013, they released an EP entitled High Rise with new lead singer Chester Bennington of Linkin Park fame.

During Stone Temple Pilots' hiatus in 1997 due to Weiland's run-ins with the law, DeLeo, his brother Dean, and Kretz joined with singer Dave Coutts of Ten Inch Men and formed Talk Show. Released in 1997 on Atlantic Records, their eponymous debut album peaked at #131 on the Billboard 200 and was considered a commercial flop. Coutts was eventually fired and the band disbanded. Weiland went into rehab and released a solo album during this time.

After Stone Temple Pilots' break-up in 2003, DeLeo and his brother Dean joined Filter frontman Richard Patrick and drummer Ray Luzier to form the band Army of Anyone. The group met after Patrick contacted the DeLeos about writing material for Filter's fourth album. The band eventually called in Luzier in for an audition, found the formula worked, and the band was formed. The band's self-titled debut album was released in November 2006. The album became a critical success; some went as far to label the album as one of the best of the year. DeLeo summed up his sound on the album as follows;