Mr. Lif (born Jeffrey Haynes) is an American hip hop artist from Boston, Massachusetts. Often noted for his political lyrics, he has released two studio albums on Definitive Jux and one on Bloodbot Tactical Enterprises. Mr. Lif is also a member of the hip hop group The Perceptionists with long-time friends and collaborators Akrobatik and DJ Fakts One.

Mr. Lif grew up in the neighborhood of Brighton in Boston, Massachusetts. After attending the Dedham, MA private school Noble and Greenough School, he went on to attend Colgate University for two years, and he eventually dropped out. He became a performer in 1994. Mr. Lif's family ancestry is Bajan.

Influenced by legendary MCs like Chuck D, KRS One, Rakim & Guru, Mr. Lif began releasing singles in the late '90s, when party rap and gangsta rap were the dominant styles for hip hop music, but Mr. Lif's lyrical agenda was a political and socially conscious one. Mr. Lif released his first single, Elektro, in 1998, attracting the attention of labels Grand Royal and Definitive Jux. Working closely with producer and Definitive Jux label head El-P, Lif released a series of critically acclaimed singles and EPs, starting with Enters the Colossus in 2000. In 2000 and 2001, he won the Kahlua Boston Music Awards for Outstanding Rap/Hip Hop Act. Touring kept him busy for the next year, but he still found time to release the Cro-Magnon single and a live CD. His track "Pull Out Your Cut" was featured in the soundtrack to the ESPN Video Game ESPN NFL 2K5.

Ian Matthias Bavitz (born June 5, 1976), better known by his stage name Aesop Rock, is an American hip hop artist and producer. He was at the forefront of the new wave of underground and alternative hip hop acts that emerged during the late 1990s and early 2000s (decade). He was signed to El-P's Definitive Jux label until it went on hiatus in 2010. The music site betterPropaganda ranked him at number 19 at the Top 100 Artists of the Decade. He is a member of the groups The Weathermen, Hail Mary Mallon (with Rob Sonic & DJ Big Wiz), and Two Of Every Animal (with Cage). Regarding his name, he said: "I acquired the name Aesop from a movie I had acted in with some friends. It was my character's name and it sort of stuck. The rock part came later just from throwing it in rhymes."

Bavitz was born at Syosset Hospital in Syosset, New York and raised in Northport, Long Island, New York to his father Paul and mother Jameija. Ian has two brothers: Chris (born 1975) and Graham (born 1977). Ian, along with his siblings, was raised Catholic but later on in his life became agnostic. Bavitz attended Northport High School in 1990 and graduated in 1994. He married Allyson Baker, guitarist and vocalist of rock band Dirty Ghosts in 2005. They now reside in San Francisco, California. The couple has now since divorced.