Sir Horace Rostill Petty (25 March 1904 – 16 February 1982) was an Australian politician.
He was born in Richmond to wood block engraver Frederick Charles Petty and Alice Maud Rostill.
He worked for the Argus as a circulation manager, and during World War II served with the AIF.
After the war he became a newsagent at Toorak; he was also an early member of the Liberal Party, and served on Prahran City Council from 1949 to 1964 (as mayor from 1951 to 1952).
In 1952 he was elected to the Victorian Legislative Assembly as the Liberal and Country Party member for Toorak.