Mandos is a term that may not have a lot of synonyms since it is a fictional name for a character in J.R.R. Tolkien's mythology. However, we can find some alternatives to express its meaning. For example, we could use the words "ruler," "governor," or "lord" to describe the power and authority that Mandos represents. Alternatively, we could use the terms "judicator" or "arbiter" to emphasize his role as a dispenser of justice. We could also use more specific words related to his domain, such as "death," "fate," or "doom," to evoke his power over the afterlife. Overall, while there may not be many exact synonyms for the name Mandos, we can use other words to convey his essential qualities and functions.