Generally ... yes.

If you do not own the rigths to the intellectual property (video game characters, titles, slogans, images, snake images, etc) US copyright law (and international equivs) make it illegal for someone that does not own that intellectual property to reproduce/distribute/market/etc (even post on message boards) that property.

Using a stranger from down the streets lawn mower to cut your grass without asking permission first is illegal ... and so is using the image/title/brand/slogan of a video game owned by someone else on a t-shirt without permission.

-adam