James Joseph Chamberlin (born June 10, 1964) is an American drummer and record producer. Described as "one of the most powerful drummers in rock," he is best known as the drummer for the alternative rock band the Smashing Pumpkins. Following the 2000 breakup of the band, Chamberlin joined Pumpkins frontman Billy Corgan in the supergroup Zwan and also formed his own current group, the Jimmy Chamberlin Complex.

In late 2005, Chamberlin joined Corgan in reforming Smashing Pumpkins; he eventually left the group in March 2009, though he returned again in 2015 for a summer tour, and has officially performed with the band since then. Following guitarist Jeff Schroeder's departure in October 2023, Chamberlin is the band's second-longest serving member behind Corgan having served the group across four separate stints. He also performed in the group Skysaw until 2012 and joined Chicago jazz saxophonist Frank Catalano for a string of 2013–15 performances in the Chicago area. An EP by Catalano and Chamberlin Love Supreme Collective was released in 2014.

Chamberlin originally trained as a jazz drummer and cites jazz musicians Benny Goodman, Duke Ellington, Gene Krupa, and Buddy Rich, as well as rock drummers Keith Moon, Ian Paice, and John Bonham as major influences on his technique, and primarily strives for emotionally communicative playing. In 2008, Gigwise named Chamberlin the 5th best drummer of all time. In 2016, Rolling Stone ranked Chamberlin 53rd on their list of "100 Greatest Drummers Of All Time".

Chamberlin was born in Joliet, Illinois, one of six children in a Catholic family of English and Hungarian ancestry. His father and his older brother Paul were both active in jazz bands, playing clarinet and drums respectively, and his brother Paul is still an active rock drummer, with a local cover band, Chasing Amy.

Chamberlin began drumming at age nine. His early instruction included Latin, Brazilian, and big band techniques, but focused on jazz, under the tutelage of Charlie Adams, known for working with Yanni.

Chamberlin dropped out of high school and left home at age 15 and joined a series of local bands, culminating in a five year stint in local show band JP and the Cats. Although his early music career proved profitable, Chamberlin's father pressured him into going to college. In 1994, Chamberlin revealed that he had been estranged from his father for seven years. After several years with JP and the Cats, Chamberlin, wearied by the touring schedule, reduced his role and got a job building custom homes with his brother-in-law. Before long, he was recruited into The Smashing Pumpkins.

The Smashing Pumpkins had been using a drum machine for early gigs, but were looking for a live drummer to open a show at Chicago club the Metro. Chamberlin and Billy Corgan met through a mutual friend, and Chamberlin expressed cautious interest, later recalling:

So I went out and saw the band – Billy, James, and D'arcy – playing at Avalon with a drum machine. Man, did they sound horrible! They were atrocious. But the thing I noticed was that not only were the song structures good, but Billy's voice had a lot of drive to it, like he was dying to succeed. So I ended up driving from work every Wednesday to rehearse with them.