A right ideal is a language L over an alphabet Σ that satisfies L = LΣ∗. We show that there exists a stream (sequence) (Rn | n > 3) of regular right ideal languages, where Rn has n left quotients and is most complex under the following measures of complexity: the state complexities of the left quotients, the number of atoms (intersections of complemented and uncomplemented left quotients), the ...