I'm currently writing in a world without humans in it - or anything related to humans - in order to give an alien feel to the world and its races. But it's hard to decide whether to include real-life animals. EDIT: It's a fantasy world, and contains intelligent races and civilizations. Just no humans. Points in favor: 1. Real animals can be easily recognized and placed in context by the reader. If you think of horses or wolves, there are immediate associations with natural habitat, behavior, relationship with other species, uses... whereas invented creatures demand a lot of cognitive work on the part of the reader, work which might be better used for understanding cultures or events. 2. Animals have mythological and archetypal significance. A valiant charge on horseback evokes feelings that a valiant charge on arbitrary herd animals does not (no matter how thoroughly you describe them). This doesn't apply to fear, though, since the unknown and bizarre is naturally frightening. 3. Is easier and would probably result in faster overall progress. Points against: 1. Imaginary animals can easily be stand-ins for real ones. You can just describe their use/behavior, which draws parallels to mules, horses, lions, etc. Every niche can be filled like this, but I'm wondering if removing ALL real-life animals from the setting is akin to kicking out the supports from under a building: leaving the reader with no easy point of reference. 2. Would fit the theme better. Now before you come in and list a dozen examples of good stories that used only the weirdest and most alien creatures imaginable, ask yourself if those creatures weren't actually part of the point. Some stories are based upon exploring strange places, in order to contrast them with the world we know (e.g. Gulliver's Travels). That's not what I'm aiming for.