Sure, she showed inklings: Poison Ivy in Batman & Robin, Emma Peel in The Avengers. But for most viewers Thurman was no more than a wispy, gawky (if sexily so) romantic leading lady. She was Kate Hudson before Kate Hudson was a thing.
Then came Tarantino’s Kill Bill—say what you want about the man, but Tarantino always puts strong female characters on screen (see also: Pam Grier in Jackie Brown; Patricia Arquette in True Romance). Even while paralyzed from the neck-down, Thurman’s Beatrix Kiddo exuded an air of coiled menace. She could ruin you and not think much about it.