A monster's alignment provides a clue to its disposition and how it behaves in a roleplaying or combat situation. For example, a chaotic evil monster might be difficult to reason with and might attack characters on sight, whereas a neutral monster might be willing to negotiate. See the Player's Handbook for descriptions of the different alignments.

The alignment specified in a monster's stat block is the default. Feel free to depart from it and change a monster's alignment to suit the needs of your campaign. If you want a good-aligned green dragon or an evil storm giant, there's nothing stopping you.

Some creatures can have any alignment. In other words, you choose the monster's alignment. Some monster's alignment entry indicates a tendency or aversion toward law, chaos, good, or evil. For example, a berserker can be any chaotic alignment (chaotic good, chaotic neutral, or chaotic evil), as befits its wild nature.

Many creatures of low intelligence have no comprehension of law or chaos, good or evil. They don't make moral or ethical choices, but rather act on instinct. These creatures are unaligned, which means they don't have an alignment.