If a standard persona is a reconstruction of your ideal customer, a negative persona is a representation of who you don’t want to target as a customer. It could be somebody who is only engaging with your SaaS product for research purposes or people who are just too expensive to acquire (due to a low average sale price or how unlikely it is they'll purchase again). Occasionally, you might see negative personas referred to as 'exclusionary' personas but it all means the same thing - profiling the people you aren’t trying to sell to.