Really, a record producer can hold alot of different roles depending on what the band or label wants from them. Mostly, the "Produced by" credit goes to the person or persons (or band) who's job it was to achieve the overall sound and feel of the recording. A producer will be in the studio listening to the music as it is being recorded and will guide the studio engineer (in some cases the producer acts as the engineer as well) and musicians towards achieving the sound that he/she wants to hear for the given music. All the Led Zeppelin albums were produced by Jimmy Page as he is the one who guided the studio engineers and techs to achieve the sound he wanted to hear on the album. The Beatles were famously produced by George Martin who also engineered the sessions. Because of the role of the producer, a producer who also has technical knowledge of the studio is preferable and will be easier to work with and/or for.
REO - record producer - was born in 1981.
Joshua - record producer - was born in 1971.
Taylor Swift's record producer is Big Machine Records.
Chris Thomas - record producer - was born in 1947.
Bob Porter - record producer - was born in 1940.
Chris Stokes - record producer - was born in 1969.
Peter Collins - record producer - was born in 1951.
Jack Ruby - record producer - died in 1989.
Chris Hughes - record producer - was born in 1954.
John Boylan - record producer - was born in 1941.
Carl Davis - record producer - was born in 1934.
The role of a producer is, he/she is the money contributer. the person who is sponsering the play, movie, etc.