Are you saying that some forms of life have no DNA whatsoever?
That depends what you call life, and what you mean by DNA. Some viruses are RNA-based rather than DNA-based, but some people don't think of viruses as life-forms. Prions don't have nucleic acids at all, but even fewer people would call them life-forms. The problem here is that we tend to define life in terms of DNA, rather than vice-versa.
There aren't any cellular organisms that don't have DNA, but that's because DNA works so well. Any DNA-less single-celled critters have long since been devoured into extinction.
The hepatitus C virus.