When the Swedish diva infected Helsinki with fever. An investigation of Ellen Hartman’s guest performance in Finland 1889During the autumn of 1889 Ellen Hartman, the star of the Royal Dramatic theatre in Stockholm, made a guest performance in Helsinki that resulted in a literal ‘Hartman fever’. This chapter is an analysis of this event and a contribution to the history of actresses, divas and celebrity studies. What did Ellen Hartman do on stage to create a success that was regarded as unsurpassed? And what expressions of admiration were seen amongst the audience?The analysis of the sources reveals Hartman’s strategy to represent herself as a diva where her performance was to be the focus, rather than the plays or their mise-en-scène. Hartman’s acting style was perceived as modern and absolutely “natural” and her embodied femininity, that was a predecessor to the so-called flapper, was a novelty. The sources also show that the audience surrounded her with processes that gave tribute to her as their chosen diva in accordance with contemporary diva codes. I argue that Hartman’s guest performance 1889 comprised both a prevision of the next century through her femininity and acting style, and on the same time was founded in a diva tradition that had long roots back in history.