Who are the names of the characters in Doom?

In the "Doom" series, the main character is often referred to as the Doom Slayer or Doom Guy, though he is sometimes simply called the Marine. Other notable characters include Samuel Hayden, a scientist and antagonist in "Doom (2016)" and "Doom Eternal," and various demons such as the Cyberdemon and the Arachnotron. The series also features the character of Dr. Betruger, a key figure in the original "Doom" games.