Nobody, really.
This is another one of those numbers that has left me shaking my head. I can't believe that a team with so many great players and such a long, proud tradition has so many uniform numbers that have never been worn by uys who were truly memorable.
The best guy I have been able to come up with for 46 is Greg Lasker, a safety for the Giant in 1986, 1987 and part of 1988. The only other one is another defensive back -- a guy I could not remember. That would be Mike Dennis, a cornerback from 1980-83. Dennis did at least intercept five passes in 1980, the only year he really contributed anything. Maybe he's the guy here.
Really, though, I can't give this nod to either of them. They just aren't good enough for this to be "their" number. At least by BBV's standards.
[NOTE: I really, really hope I haven't missed anyone obvious this time. As far as I can tell, having checked multiple sources, this is just one of those 'blah' numbers for the Giants. If you know of one I missed, of course we all want to know.]