Teemu Keisteri (born 22 August 1985) is a Finnish visual artist and DJ who is known for his stage persona Windows95man. As a visual artist, he gained recognition in Finland for creating the character Ukkeli (lit. 'Old man') in 2008. As a DJ, his artistic style and appearance draw inspiration from the late 1990s, during which the Windows 95 operating system was produced. He is set to represent Finland in the Eurovision Song Contest 2024 with the song "No Rules!", featuring Henri Piispanen.
Keisteri has studied photography at the Institute of Design in Lahti. He has said that he learned during his studies that he is more of a visual artist than a photographer. He is also known as a video artist, dance performer and DJ. Keisteri has his own art gallery called Kalleria in Kallio, Helsinki.
Keisteri participated as Windows95Man with Henri Piispanen (vocals) in the 2024 edition of Uuden Musiikin Kilpailu, with the song "No Rules!". Despite finishing last in the jury voting, he came first overall with 313 points thanks to the televote in Finland. He was thus selected to represent his country in the Eurovision Song Contest 2024.