Hildegard Breiner (* March 28, 1936 in Bregenz) is an Austrian activist in the anti-nuclear movement in Austria.
Hildegard Breiner is from Vorarlberg, Austria, where she and her late husband led the anti-nuclear campaign against Zwentendorf Nuclear Power Plant in the 1970s. In 1978, an unprecedented 85 percent of the voters in Vorarlberg cast their votes against Zwentendorf, tipping the scales of the nationwide referendum. In the second half of the 1980s, Hildegard Breiner played a major role in opposition to the nuclear Wackersdorf reprocessing plant (WAA) to be built at Wackersdorf in neighbouring Bavaria, Germany.