A protege of 9th Wonder who worked with Lamar when he was still best known for his mixtapes, Rapsody is a long-underrated female MC that provides the album with one of its most memorable guest verses. "Twelve years of age, thinking my shade too dark/I love myself, I no longer need Cupid/And forcing my dark side like a young George Lucas/Light don't mean you smart, being dark don't make you stupid," the 27-year-old Rapsody spits on "Complexion (A Zulu Love)," which focuses on skin color in the African-American community.
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The West Coast legend has always been vocal about his support of K. Dot, telling MTV, "I love his success, I love his story, his hustle," when good kid, m.A.A.d city was released. After both artists appeared on Flying Lotus's 2014 album You're Dead!, they entered the studio together in February; as we know now, the session was to lay down verses on "Institutionalized," where Snoop quickly appears to tell an origin story: "And once upon a time in a city so divine/Called West Side Compton, there stood a little n--a/He was five-foot-something, God bless the kid/Took his homie to the show, and this is what they said…"
Wise is credited as a guest on the back-to-back tracks "Institutionalized" and "These Walls," after the relatively unknown vocalist (who also performs with indie duo Sonnymoon) appeared on good kid, m.A.A.d city's "Real," and did background vocals on several other tracks from that album. Sonnymoon (who happens to be releasing an album next week) does eclectic electro-pop, with Wise's vocals distorted by varying combinations of loops and synths. Wise also joined Lamar on The Colbert Report last December to premiere an untitled song, which does not appear on To Pimp a Butterfly, on the show.
A veteran Los Angeles rapper and producer who collaborated with Lamar on good kid, m.A.A.d city standouts "Real" and "m.A.A.d city," Terrace Martin returned to the studio with Kendrick after producing songs by YG, Talib Kweli and fellow TDE rapper Ab-Soul, among others. Martin's production is even more present on To Pimp A Butterfly, drawing upon his fiercely loved jazz and funk music (he cites Miles Davis, Herbie Hancock and John Coltrane as primary influences) to help construct Lamar's latest soundscape.
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The Grammy-winning vocalist and "First Daughter of Soul" (her father is Donny Hathaway) appears on To Pimp A Butterfly as a backing vocalist on "Complexion (A Zulu Love)," but more importantly, her 2008 song "On Your Own" serves as part of the foundation of album standout "Momma." A veteran of the industry, Hathaway has been making serious waves in the jazz/hip-hop/R&B world for years, and gets a well-deserved nod from Lamar on the album.
A former member of the Soulquarians -- the turn of the millennium collective that also included Erykah Badu, The Roots, late great producer J. Dilla and other left-thinking hip-hop and soul artists -- Bilal is the male singer featured on "Institutionalized" and "These Walls." Born Bilal Sayeed Oliver in Philly, the 35-year-old's debut, 1st Born Second, featured production from Dr. Dre, Dilla, Raphael Saadiq and others. After multiple delays and disagreements with Interscope about his unreleased second album, Love for Sale, Bilal left the label, but kept busy by contributing his virtuosic singing to tracks by Common, Jay-Z, Lupe Fiasco, Kimbra, the Clipse and many others. His last album, the independently released A Love Surreal, was issued in 2013.
The producer behind "Wesley's Theory" is already a legend to some -- a godfather in the Los Angeles beat scene and the creator of several acclaimed albums, including last year's You're Dead!. Born Steven Ellison, FlyLo first gained notoriety when his spicy, bass-heavy beats were featured in spots on the Cartoon Network's Adult Swim. Ellison has a serious family pedigree: He is the grand-nephew of the late jazz pianist Alice Coltrane and the cousin of musician Ravi Coltrane. His grandmother is singer/songwriter Marilyn McLeod, who wrote Diana Ross's "Love Hangover." He also has a rapper alter ego Captain Murphy -- he tweeted that "Wesley's Theory" was originally intended for a new project under that pseudonym.
Ron Isley, who pops up alongside James Fauntleroy on "How Much A Dollar Cost," is a soul legend with surprising staying power. His work as co-founder of Isley Brothers already made him an icon -- they landed created dozens of R&B hits, won a Grammy for their 1969 classic "It's Your Thing" and made "Twist and Shout" a hit before the Beatles. In the 90s he saw an unlikely resurgence by collaborating with R. Kelly in a saga of songs including the classic "Down Low (Nobody Has to Know)" that featured Isley taking on the alias Mr. Biggs. He's been your favorite rapper's favorite guest vocalist for years, working with UGK, Snoop Dogg, Nelly, Nas and more. From 2007 to 2010, he was imprisoned for tax evasion.
Thundercat (real name: Stephen Bruner) is a singer and songwriter, but he's mostly known for his truly virtuosic bass guitar playing. He recorded on Erykah Badu's two New Amerkyah albums, but rose to a higher level of fame with his whirlwind bass solos on Flying Lotus' 2010 opus Cosmogramma. In 2013, he released his second studio album Apocalypse on Lotus' Brainfeeder imprint, which featured him singing and playing bass; the album included "Tron Song," a bizarre ode to his pet cat. Here, he shows up to make the songs "Wesley's Theory" and "These Walls" even spacier.
Lamar's idol looms large over To Pimp A Butterfly before its final track, as Kendrick touches upon the urgency and social ideas of Pac's career while extending his West Coast hip-hop sound (the new album's release was also timed to the 20th anniversary of Me Against The World). On the finale "Mortal Man," however, the influence becomes an unlikely collaborator: the 12-minute track ends with Lamar "interviewing" Shakur, asking the deceased rapper questions about opportunity and evil, in an effort to understand his own place as a hip-hop leader. In a harrowing final move, the album ends with Lamar calling out "Pac," pleading to spend more time with his hero.