Sonia Henie's hardest junp element was two single Axels in sequence. She did her single Lutz in the opposite direction from her spins and other jumps.
Besides all of her titles -- she took on all challengers for ten years and never lost -- she then brought figure skating to Holltywood and created the first fusion of competitive level skating and show business, turning the sport into world-wide entertainment.
There are several skaters who deserve mention in all-time great discussion. Cecelia Colledge was the first lady to do a double jump -- can you believe it? TWO complete revolutions! -- she almost nipped Henie at the 1936 Olympics and would have been the favorite for the gold medal in 1940 as well as probably 1944 if the Olympics had been held in those years.
Carole Heiss has five World Championships and two Olympic medals, one gold and one silver. She is the first woman to do a double Axel. (Not to mention, she starred in the movie Snow White and the Three Stooges -- you have to know how big the Three Stooges were, especially Curly, in the U.S. to fully appreciate that achievement.

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Herma Szabo won 7 world championships (5 in singles and 2 in pairs) and the 1924 Olympic gold medal. She retired after the 1927 judging scandal where Henie won the world championship by receiving first-place ordinals from the three Norwegian judges on the panel of five, , while Szabo won the votes of the two German-Austrian judges.
And of course Madge Syers won the silver medal at the 1902 World Championships when the ISU was unable to find an explicit rule that said women were not allowed to compete in skating contests. (It was just taken for granted -- who would ever imagine such a thing?!)
She won the (then newly minted) ladies' event at the 1908 Olympics. Her tech score was totally dominant, drawing raves for "the wonderful accuracy of her figures, combined with perfect carriage and movement." In the free skate, she "excelled in rhythm and time-keeping."
Hah! I bet Anna Shcherbakova and Alexandra Trusova would not dare to go up against Syers in a "perfect carriage and excellent time-keeping" contest.
Edit: Come to think of it, Anna
could compete in the rhythm and time-keeping segment, based on the dance videos she has posted.