Jaques Morelenbaum ((Portuguese pronunciation: [ˈʒakiz moɾelẽˈbɐ̃w]) born 18 May 1954) is a Brazilian instrumentalist, arranger, conductor, composer and music producer.

Morelenbaum was born in Rio de Janeiro, the son of conductor Henrique Morelenbaum and piano teacher Sarah Morelenbaum. His siblings are Lucia Morelenbaum, clarinetist in the Brazilian Symphony Orchestra, and Eduardo Morelenbaum, conductor, arranger and instrumentalist. He is married to singer Paula Morelenbaum.

He started his musical career as part of the group A Barca do Sol, and participated in the Nova Banda that performed live with Antonio Carlos Jobim and in recordings that led to a Grammy win for the CD Antonio Brasileiro. As a cellist, he studied music in Brazil and later attended the New England Conservatory of Music. In 1995, with Paula Morelenbaum, Paulo Jobim and Daniel Jobim he created the Quarteto Jobim Morelenbaum. The group has toured Europe several times, including an appearance at the Expo'98 held in Lisbon. They have also toured the United States and Brazil, and have recorded a CD (Quarteto Jobim Morelenbaum).