What's this on the bottom left corner of my iMac screen?

[LoganT]

The only way I can see this if I use a solid color as a background. It shows up if I restart and it shows up in Windows in BootCamp so it's obvious a hardware issue.

 

[JNB]

First, please use the {TIMG} tag instead of {IMG} tags. Cuts down on bandwidth.

The photo's out of focus so it's hard to tell what's an artifact and what's reflection. I take it you're talking about the line and dark gray streaking beneath it? I'd say it's time to call or visit your nearest Apple Store. That appears to be in the screen itself