Robert Armstrong may refer to:
Arts and entertainment
Robert Armstrong (actor) (1890–1973), film actor
Robert Armstrong (cartoonist) (born 1950), American underground comics artist and musician, coined the term "couch potato"
Fictional characters
Robert Armstrong (Home and Away), character in the Australian soap opera
Robert Armstrong (Noble House), a character from the James Clavell's novel
Government and military
Robert Armstrong (Australian politician) (born 1952), member of the Tasmanian Legislative Council
Robert Armstrong (Northern Ireland politician) (1888/9–1961), member of the Senate of Northern Ireland
Robert Armstrong (military officer) (1792–1854), officer in the United States Army
Robert Armstrong, Baron Armstrong of Ilminster (1927–2020), British member of the House of Lords and former civil servant
Robert Baynes Armstrong (1785–1869), British Member of Parliament for Lancaster
Robert E. Armstrong (1925–2008), American mayor of Fort Wayne, Indiana
Robert P. Armstrong (born 1938), Canadian lawyer and judge
Other
Robert Armstrong (baseball) (1850–1917), American professional baseball player
Robert Armstrong (cricketer) (1836–1863), English cricketer
Robert Armstrong (racehorse trainer) (1944–2021), British racehorse trainer
Robert Archibald Armstrong (1788–1867), Gaelic lexicographer
Robert C. Armstrong, chemical engineer at MIT
Robert John Armstrong (1884–1957), fourth Bishop of Sacramento