Jussi Sydänmaa (born 26 June 1972) is a Finnish guitarist and a former founding member of the rock band Lordi, performing by the stage name of Amen until his departure in May 2022.

He graduated as an Information Technology engineer in 2001 and worked on Lordi's website. Sydänmaa plays Schechter guitars (specifically the Solo II Custom and the Hellraiser Solo II). The municipality of Mäntsälä granted Sydänmaa with a statue named "Hard Rock Stone" on 26 June 2006.

Sydänmaa has been featured as a special guest on Markus Striegls concert in 2011 and Doro Pesch's concert in 2014. He has also recorded guitar riffs which were used by Ari Pulkkinen to create the soundtrack for the video game Shadowgrounds. His acoustic guitar solos "Amen's Lament to Ra" and "Amen's Lament to Ra ll" were included on Lordi's albums Babez for Breakfast and Scare Force One.