Skeleton

The Skeleton is a mob that spawns naturally in the Diamond Reserve and Obsidian Sanctuary of the Deep Caverns, as well as on the Player's Private Island at night. Additionally, they can be found at the Gravel Ravine in the Spider's Den, in the High Level area, or spawned by a Skeleton Minion.

Skeletons drop bones upon being killed and occasionally a bow.

Depending on where the skeleton is found, it may have armor or an enchanted bow.

Skeletons spawned in the Spider's Den or the High Level will drop a special bone that spawns skeletons every 5 seconds. This bone will not be picked with Telekinesis unlike all other bones dropped by the skeleton. This can be useful as not picking them up will spawn skeletons every few seconds, allowing skeletons to build up, making a great bone grinder if farmed with a bow. Skeletons tend to spawn faster in the Spider's Den during nighttime, but still spawn during the day, making this a great spot to farm bones and experience.

Strategy
Either run straight at the skeleton to kill it or fight it from afar. If you're going to make use of the special bone in the Spider's Den, then fill your entire inventory of random items that are not arrows so as to not pick it up. (strategy for spooky event)

Another Spooky Event related strategy is attracting a horde of Skeletons to occasionally shoot Silverfish and sitting on a Rock Pet to prevent knockback. from there you can start killing the Silverfish to farm candy or kills for a Raider Axe. This strategy also works with the Watchers shooting Endermite in The End although you'll need stronger gear to survive their attacks