Jonathan Fa'afetai Lemalu (born 1976) is a New Zealand bass baritone opera singer. Born to Samoan parents who had emigrated to New Zealand, he was educated in Dunedin. His first singing teacher was Honor McKellar, who began teaching him while he attended Otago Boys' High School. He studied both Law and Music at the University of Otago, graduating with a Bachelor of Laws in 1999.

Lemalu studied at the Royal College of Music (RCM), where he won the college's gold medal award in 2002. He won the prestigious London-based Kathleen Ferrier Award (previously won by Malvina Major in 1966) that same year. He was a BBC Radio 3 New Generation Artist from 2002 to 2004. He was the 2004 winner of the Royal Philharmonic Society's award for Young Artist of the Year. At the 52nd Annual Grammy Awards Lemalu was a co-recipient of the Grammy Award for Best Opera Recording for his work on Benjamin Britten's Billy Budd.

He returned to New Zealand to perform in the 2012 New Zealand Festival of the Arts in Wellington. He took the part of Te Kumete in the opera Hōhepa by Jenny McLeod which told the story of political prisoner Hōhepa Te Umuroa. In 2013 he was awarded the Senior Pacific Artist Award at the Creative New Zealand Arts Pasifka Awards.

Lemalu was made a Fellow of the Royal College of Music (FRCM) in 2022 in recognition of his services to music and to the College.

Lemalu's wife is a Croatian family therapist, Sandra Martinović. They live in London with their son Joshua and daughter Arabella. He is currently a professor of Vocal Studies at the Guildhall School of Music and Drama.