Jari Mäenpää is a Finnish singer, multi-instrumentalist and songwriter. He is the founder of heavy metal Wintersun for which he records all instruments except the drums. Before forming Wintersun, Mäenpää was also known for his role in the folk metal band Ensiferum, which he joined in 1996 after leaving his prior band named Immemorial. Wintersun was initially planned as a parallel project alongside Ensiferum, but in January, 2004 he was forced to leave Ensiferum due to clashes between their touring schedule and the studio recording time he had booked for Wintersun.

Wintersun is a Finnish heavy metal band from Helsinki originally formed as the side project of Jari Mäenpää, then-vocalist and guitarist of folk metal band Ensiferum.