In my field (Epidemiology), when doing Bayesian analysis, it is very common to set one's priors to be a distribution. Sometimes the point estimate and spread of a previously conducted study or meta-analysis, sometimes merely a uniform distribution with upper and lower bounds ("It is extremely unlikely that the relative risk of disease for this exposure is below 0.01 or above 100...")

It's been argued that frequentist analysis is essentially a Bayesian analysis with a prior distribution centered on zero with bounds from positive to negative infinity.