Theatre director Tiit Ojasoo and interdisciplinary artist Ene-Liis Semper are the founders in 2005 and since then the two artistic directors of Theatre NO99. The two have formed an indispensable duo that together with the actors of Theatre NO99 has changed Estonian theatre and has received considerable aclaim for their work across Europe. Ojasoo and Semper work in various formats, from doing productions that are presented in offices and other non-stage situations, to work presented in television, to film, to big scale stage productions for thousands of spectators at a time. Their works often combine visually expressive staging with fearlessly addressing the most complex societal issues.

Tiit Ojasoo (1977) studied directing at the Estonian Academy of Music and Theatre, graduating in 2000 and has since been considered by many to be the most renowned theatre director in Estonia. He often devises productions from scratch together with the troupe of Theatre NO99, but he also works with plays, having staged Shakespeare, Stoppard, Albee, Koltes and Jarry. His work at Theatre NO99 and at other theatres has repeatedly been awarded Estonian yearly theatre awards for Best Director.

Ojasoo's and Semper's work at Theatre NO99 has been invited by international festivals such as Festival d’Avignon (France), Wiener Festwochen (Austria), Theaterformen (Germany), NET (New European Theatre) and Golden Mask (Russia) and has been performed at venues throughout Europe such as Théâtre de l'Odéon in Paris, HAU in Berlin and Thalia Theater in Hamburg.

In addition to Theatre NO99 Tiit Ojasoo's and Ene-Liis Semper's international career has over the years included also working at Münchner Kammerspiele and Thalia Theater Hamburg (Germany) where one their latest work was Peter Handke's „The Hour When We Knew Nothing Of Each Other“ that premiered in April 2015. That production was invited to Wiener Festwochen (Austria) and Ruhrfestspiele (Germany, both on 2015) and lately opened the Holland Festival (Netherlands, 2016). The latest piece was "Hänsel und Gretel" that premiered in April 2018.

It has been noted by many that a very central trait of Semper’s and Ojasoo's work as a director is the high level of scenic energy of his actors and also that the actors work as a well tuned ensemble. One of the specific qualities of his work is also the ability to develop societal metaphors out of very personal experiences and emotions.