Guitarfish (also known as guitar sharks or shovelnose-rays) are members of the Rhinobatid family and are technically rays that have evolved a shark-like form. What distinguishes sharks and rays is the join of the pectoral fins (the ones at the side - in this case they look like wings) to the body. If it joins at the head in front of the gills it's a ray, behind is a shark.
This is a Long-Snout Shovelnose Ray (Aptychotrema rostrata) from Jervis Bay, Australia
Whilst these are Rhinobatus halavi from Marsa abu dabab, Egypt which is where I found some of the turtles for the Turtle-y awesome post.
On South Africa's Protea Banks there is a dive site called Guitar shark Alley where squadrons of 2 metre plus Giant Guitar sharks line up like aircraft. Unfortunately when I dived this site conditions made it impossible to get to the area in question so I didn't see them although this gives me an excuse to go back of course.