Bandit Marauders are one of many types of bandits that roam the wilds of Skyrim. They are the most powerful variant of generic bandit, excluding boss level Bandit chiefs. They are commonly found in groups with other bandits of varying sub-type.
Bandits can be found in locations all over Skyrim (e.g. Pinewatch in Falkreath Hold in southern Skyrim). They are usually found in groups and are found wearing low-level armor and using low-level weapons like iron armor and a steel mace, however their gear is often superior to that of lower-ranking bandits. High-level players will be able to dispatch these enemies very easily as they have little to no magical resistance or high skills.
The items lootable off their corpses vary wildly. Sometimes they carry quest items, treasure maps, gold or gems or less valuable items like apples or low-level weapons. They can be useful because they are numerous and they can help in leveling combat skills like One-Handed or Destruction.