I spotted an assassin bug on our back deck one afternoon - although I didn't know what it was at the time. I had only seen a few similar bugs in the past. There are quite a few different species that don't necessarily look the same. They can have different colors as well as shapes. One thing they all do have in common is that big feeding tube for a mouth which they use to inject saliva into their prey to liquify it, then suck out its insides. If bitten, the bite can be very painful and, in some cases, what wikipedia called "medically significant."
Some of these photos look like two different bugs, but they are all the same one. The white hairs showed up more on some photos than others.
The hairs serve to keep the prey stuck to them.
The long, probe-like mouth is also seen better in some images than others.