Marieke Katherine D'Cruz (née Guehrer; born 9 February 1986) is an Australian swimmer who is the former world record holder in the 50 metres butterfly short course.

She clocked 24.99 seconds[1] After her breakout meet in late 2008, D'Cruz broke her personal best times in several events, also breaking the short course 50 m butterfly world record.

The next day she clocked 25.60 s in the 50 m Butterfly, easily making the qualifying time and becoming the third fastest in history in that event, after some thunderous times posted in the semi-finals, the fasted qualifiers failed to match their times in the final, and Guehrer won gold.

With a tremendously fast semi-finals in the 50 m butterfly, from lane 6 Guehrer caused an upset capturing gold.

At the 2010 Commonwealth Games, D'Cruz won silver in the 50m butterfly final to Francesca Halsall and won gold in the 4×100 m freestyle relay.