What does an external hemorrhoid look like?

Varies. If it is just swollen, it may look just like a boil and be red and tender near anus, if it is thrombosed it will be even more tender and appear as a dark purple grape near the anus. If you have either, get it checked by an expert.
Brown bump. An external hemorrhoid looks like a brown bump on the colored part of the anus. They can be very small or they can grow quite large. When small, they are usually painless. They generally become more uncomfortable and itchy as they grow larger.