Melanie Johnston-Hollitt (born Melanie Johnston; 8 September 1974) is an Australian Astrophysicist.
She is known for having worked on the design, construction, and international governance of several major radio telescopes including the Low Frequency Array (LOFAR), the Murchison Widefield Array (MWA) and the upcoming Square Kilometre Array (SKA).
She is currently Director of the Murchison Widefield Array and a full Professor at the Curtin Institute of Radio Astronomy at Curtin University and the International Centre for Radio Astronomy Research.