If you're searching for alternatives to describe someone as "not all there," there are several other phrases you can use. A few options include "a bit off," "not quite right," "eccentric," "strange," "odd," "unbalanced," or "quirky." Each of these words represents a different way to describe someone who may not be completely present in their thoughts or actions. Whether it's a friend or acquaintance who seems a bit out of touch with reality or a coworker who regularly has off-beat ideas, there are many ways to describe someone who may not seem "all there." Experiment with different words to capture the nuances of their personality.