Murder one usually refers to first-degree murder.
Murder One may also refer to:
Film and TV
Murder One (film), a 1988 biographical crime drama film
Murder One (TV series), American legal serial broadcast on ABC in 1995–96
Murder 1 (film), first installment, in 2004, of Bollywood film series, Murder
Music
Murder One, album by Paul Di'Anno
Murder One, former band of a member of Mob Rules
Murder One, bass amplifier head blown up by Lemmy
Murder One Records, label for Sean T
Songs
"Murder One", song by 50 Cent from The Lost Tape
"Murder One", song by Metallica from Hardwired... to Self-Destruct
"Murder One", song by Sodom from In War and Pieces
Other
Murder One (bookshop), book store in London, open from 1988 to 2009
Heroin (slang)