In Bulgaria, the first season of "Big Brother" was aired in 2004 on Nova Television, and quickly became one of the most successful TV formats in the country. Niki Kanchev was the main presenter in all editions, except for "Big Brother 4", where he was replaced by Milen Tsvetkov. Evelina Pavlova was a co-host in the period 2004–2006. Five main seasons, seven celebrity seasons, four All Stars seasons and a Family season have been produced so far. The fifth main season premiered on 17 August 2015 and was the first non-celebrity season to be produced in seven years.