Frederick William Mallalieu (1860 – 10 May 1932) was a Liberal Party politician in the United Kingdom.
He was elected as the Member of Parliament (MP) for Colne Valley at a by-election in 1916. He was re-elected as a Coalition Liberal at the 1918 general election, when because of his support for Lloyd George's Coalition Government, the Conservative Party did not field a candidate.
However, a Conservative candidate did stand at the 1922 general election, and Mallalieu was reduced to third place, losing his seat to the Labour Party's Philip Snowden. His share of the vote had fallen from 58.8% in 1918 to only 25.1% in 1922.
Mallalieu did not stand for Parliament again, and died in 1932, aged 71.
Two of his sons were elected to the House of Commons:
Joseph's daughter Ann has been a Labour life peer since 1991.