A "White Whale" in Destiny is that one raid weapon that, for some reason, you just can't seem to get. And even if it's total shit, you want it because you have the other 8.

I now am OFFICIALLY a Collector.

I have all the Exotic weapons, all the Exotic armors, all the Vault of Glass raid armors, all the Crota's End raid armors, and all the VoG and Crota raid weapons.

And if I don't have them, I've had them previously.

It took me 29 completions of Vault of Glass on Hard to get the Praetorian's Timepiece pulse rilfe. And 30 completions of Crota's End on and difficulty to get the Hunger of Crota rocket launcher.