Henry Pineau (January 22, 1863 – February 18, 1904) was a Canadian politician, who represented the electoral district of 1st Prince in the Legislative Assembly of Prince Edward Island from 1899 to 1900.^[1] A member of the Conservative Party, he was most noted for crossing the floor to vote with the governing Liberals on a crucial motion of non-confidence in early 1900.^[1]

A farmer and fisherman in Miminegash, Prince Edward Island, Pineau was elected to the legislature in a by-election in 1899, after the election of Meddie Gallant in an 1898 by-election was overturned by the courts.^[1] However, he was rarely actually present in the legislature^[1] until the confidence crisis of early 1900, when the government of Donald Farquharson was threatened by MLA Joseph Wise's attempt to withdraw his earlier resignation;^[1] Wise attempted to vote with the Conservatives, which would have brought down the government, but his vote was disqualified by speaker James Cummiskey.^[1] Pineau then crossed the floor to the Liberals, ensuring the government's survival on the vote.^[1]

Pineau did not run for reelection in the 1900 general election.^[1] He died on February 18, 1904, in Miminegash.^[1]