Blackadder is a surname. Notable people and fictional characters with this surname include:
People
Agnes Forbes Blackadder (1875–1964), Scottish medic Charles Blackader (1869–1921), British general in the First World War Elizabeth Blackadder (1931–2021), Scottish painter John Blackadder (preacher) (ca. 1622–1685) Scottish Presbyterian Covenanter preacher John Blackadder (soldier) (1664–1729), Scottish soldier Robert Blackadder (d. 1508), medieval Scottish cleric, diplomat and politician Todd Blackadder (born 1971), New Zealand rugby player
Fictional characters
Edmund Blackadder, various related characters on Blackadder Vivian Blackadder, on JAG