Ellen Osiier (13 August 1890 – 6 September 1962) was a Danish foil fencer. Osiier was born in Hjørring, Nordjylland, Denmark. The 1924 Summer Olympics in Paris was the first Olympic Games to feature women's fencing. Osiier, then 33, won the gold medal and went undefeated in the 16 matches she fenced in the event. With this victory, Osiier became the Olympics' first woman fencing champion. Her husband, Ivan Osiier, fenced in seven Olympics, won a silver medal in individual épée for Denmark at the 1912 Olympics, and won 25 Danish national championships in three weapons.