Alicia Silverstone "bummed everyone out" when they realised she was nothing like her airhead character in Clueless.

The actress was cast as superficial high school student Cher Horowitz in the 1995 comedy, and Alicia claims she struggled to prove her intelligence after the film became a hit.

The 35-year-old star worked hard to shake the phony image long afterwards - much to the annoyance of Clueless fans.

"I remember doing interviews in London for some movie at the time, and the interviewers would want to talk about the movie, of course, but all I wanted to talk about was murder," she explained in an interview with Bullett magazine.

"They probably expected me to be like the Clueless character, but instead I was sitting there saying stuff like, 'And then they anally electrocute!' I pretty much bummed everyone out."

The movie's director Amy Heckerling thought Alicia was the perfect actress to portray Cher. The filmmaker says the blonde star had a great mix of likeability and sass.

"When I was writing the script for Clueless, I had a vague notion in my head of Cher as a pretty, sweet blonde, who, in spite of being the American ideal, people still really like. You had that Marilyn Monroe thing, which is that other women love you, too," she explained to the magazine.