Mart Dayne McChesney (January 27, 1954 – January 14, 1999) was an American television and film actor known for his appearances in Star Trek: The Next Generation as the tar creature, Armus, in "Skin of Evil" (1988), and as Sheliak in "The Ensigns of Command" (1989). For both appearances he wore heavy prosthetics and costumes. Footage of his appearance as Armus was re-used in the Star Trek: The Next Generation second season episode "Shades of Gray" (1989).