A systems language written by 
Ken Thompson in
1970 mostly for his own use under 
Unix on the 
PDP-11.  B
was later improved by Kerninghan(?) and Ritchie to produce
C.  B was used as the systems language on 
Honeywell's
GCOS-3.
B was, according to Ken, greatly influenced by 
BCPL, but the
name B had nothing to do with BCPL.  B was in fact a revision
of an earlier language, 
bon, named after Ken Thompson's
wife, Bonnie.
["The Programming Language B", S.C. Johnson & B.W. Kernighan,
CS TR 8, Bell Labs (Jan 1973)].