Robert O'Neil "Bob" Forrest (born February 15, 1961) is the lead vocalist and lyricist for Los Angeles bands Thelonious Monster and The Bicycle Thief. In September 2006 he released his first solo album, Modern Folk and Blues Wednesday. He is also a drug counselor, appearing alongside Dr. Drew Pinsky on Celebrity Rehab and Sober House.

Forrest is the former Chemical Dependency Program Director at Las Encinas Hospital. In 2010, he and co-founder Shelly Sprague launched Hollywood Recovery Services.

Forrest is also well-known as a close friend of Red Hot Chili Peppers bandmates Flea and Anthony Kiedis who was once a drug buddy to Forrest and who later got clean with Forrest's help. The Red Hot Chili Peppers and Forrest's bands also have a longtime connection. In 1988, John Frusciante was originally intended to join Thelonious Monster. However, he joined the Red Hot Chili Peppers instead while current Chili Peppers guitarist, Josh Klinghoffer played with both Thelonious Monster and The Bicycle Thief. Forrest has performed many times with the Red Hot Chili Peppers dating back to the mid-1980s and most recently in 2009 at an awards event honoring Kiedis for his commitment to helping other addicts with the addiction and recovery process. Forrest was also one of the last people to see actor River Phoenix alive the night he died of a drug overdose.

In 2008, he began releasing a series of live digital EPs exclusively at his official website. Forrest is the subject of Bob and the Monster, a documentary about his music career and battles with drug addiction. The documentary was released in March 2011 and continues to play on the film festival circuit. The DVD was released in September 2013.

Forrest released a new album, Survival Songs, on October 9, 2015 which was produced by Grammy-winning producer, Ian Brennan. It is a folk album featuring new material and folk versions of existing Thelonious Monster and Bicycle Thief songs.

In 2018, Bob Forrest released a career spanning live record via Greenway Records. The first live album from L.A. legend Bob Forrest: “Bob Forrest + Friends Live 2016,” features Forrest’s past and present bandmates including Zander Schloss (Thelonious Monster, The Circle Jerks, Joe Strummer) Mike Martt (Thelonious Monster, Tex And The Horseheads), Josh Klinghoffer (The Bicycle Thief, Dot Hacker, Red Hot Chili Peppers), and Josh Blum (The Bicycle Thief, Sugartooth).