Swedish musician (he mainly plays electric bass and double bass) and songwriter, born 26 February 1973 in Kung Karls parish in Västmanland County.

Hielm is active in the Mats / Morgan Band and the bass duo Bas & Bas together with Bengt Jonasson. He has previously been a member of Pain of Salvation, Charter 77, Meshuggah and has as a session musician played with Devin Townsend, Trey Gunn, Napoleon Murphy Brock and Denny Walley from Frank Zappa's band, Dark Funeral, Tina Ahlin, Wille Crafoord and Stefan Sundström. He has also been active as a composer for dance theater and television.

Gustaf Hielm mainly plays instruments from Yamaha, NS Design and British Wal.