This comparative study focuses on the detective genre and is conducted through literary analysis with a feminist critical perspective of two of its most iconic protagonists, Sherlock Holmes and Miss Marple, created by Sir Arthur Conan Doyle in 1887 and Agatha Christie in 1930 respectively. The purpose is to attempt to establish the effect of the gender differences on these two protagonists. Both Holmes and Miss Marple are deemed as iconic in the detective genre, but the protagonists do not have similar experiences and are created by authors of different genders. Thus, the focus is to explore how gender differences are represented in the literary texts A Study in Scarlet (1887), “A Scandal in Bohemia” (1891), and The Murder at the Vicarage (1930) when it comes to their work as detectives. By using a feminist critical perspective and with the help of previous research, the differences in three central issues, that is, work methods, attitudes and method of disguise, are established. The most prominent result from the analysis is that Miss Marple has to work independently from the police force and trust another character, Leonard Clement, with what she knows hoping that Clement will use her observations to make the case move forward. By contrast, Holmes is approached by clients and even assists the police force in investigations, while Miss Marple is dismissed because of gender discrimination and ageism when she reaches out to the police force. Miss Marple is clearly a victim of gender discrimination and ageism, while Holmes is seen as eccentric but fully competent as a detective. Holmes is even described as having “extraordinary powers” while Miss Marple is described as an “old pussy” in a derogatory manner. Therefore, the results are that there is a significant difference in attitude where Holmes as a man encounters more positive attitudes and Miss Marple as a woman encounters more negative attitudes, all because of gender discrimination and ageism. These results are of great importance as it reveals what gender differences Holmes and Miss Marple encounter in their literary texts. It opens up the opportunity for more research in gender differences and gender discrimination in comparisons between protagonists. That Miss Marple is successful in the end, however, functions as a feminist statement.