NiceMan Dan is a character in Sparks Nevada, Marshal on Mars. He has been played by Jim Beaver in Mortified on Mars, and in an unpodcasted version of The Great Thrilling Adventure Hour / Welcome to Night Vale Crossover. In the podcasted version of the Crossover, NiceMan Dan was played by James Urbaniak.
NiceMan Dan is Highwayman Dan's father, is exceedingly polite, and always plans ahead. He raised his boy with a firm hand, and isn't sure where he went wrong. By trade, he is a shoemaker.
In Mortified on Mars, NiceMan Dan sneaks into the camp which Sparks Nevada, the Barkeep, Pembroke Cartwright, and Alex Cartwright made after defeating and capturing Highwayman Dan the evening before, during their hypercattle drive. NiceMan Dan knocks out Sparks Nevada, who was on watch, then steals the hypercattle, the Barkeep, who had been stabbed by Highwayman Dan earlier in the night, and his son, Highwayman Dan. When Sparks catches up with them, NiceMan Dan says that his well-planned scheme is a lesson to Highwayman Dan to show the benefits of planning ahead.
NiceMan Dan and Highwayman Dan are both wearing jetpacks, so when NiceMan Dan removes the gravity in the area, they safely fly away. It's unclear whether they were later caught or if they got away with the hypercattle, as they failed to kill Nevada and his friends.