Likely Enemies

These creatures appear very frequently and are excellent thematic picks:

Kobolds – The most frequently appearing foe by a wide margin. Perfect for a ranger who’s spent time in warrens or delving ruins.
Goblins – A staple in nearly every dungeon crawl. Appear regularly in wilderness and underdark settings.
Orcs – Very common, especially in the deeper encounter charts. A classic adversary.
Zombies – Numerous undead encounters suggest a ranger who's a bane to the restless dead.
Skeletons – Like zombies, another prime undead type that appears in many night and dungeon tables.

These enemies show up consistently, but with less dominance than the top tier:

Hobgoblins – Present in several encounters, often in patrols or guarding areas.
Stirges – Nuisance creatures that show up in numerous tables, especially underground.
Giant Rats – Frequently found in sewers, crypts, or ruined keeps.
Giant Centipedes & Crab Spiders – Appear often and are solid picks for vermin-hunters.
Berserkers – Humanoid, likely crazed cultists or wild warriors. Found in various encounters.
Trolls – So many trolls!
Undead (General) – Ghouls, Crypt Shades, Ghostly Skiffs, etc. Suggesting undead as a favored category would be fitting for a more generalized hunter of the dead.

Good for flavor or if your ranger has a specific background or campaign hook:

Lizardfolk – Recur in one table strongly, useful if the campaign is swampy or tribal-focused.
Bug Bears – Fairly frequent in some locations.
Bats (Normal and Giant) – Appear in a few places; better if your ranger specializes in cave ecosystems.
Spitting Cobras / Beetles / Insect Swarms – Makes for a more "jungle or wasteland" ranger.
Slimes/Oozes (Gray, Ochre, etc.) – Appear several times; this could be unique if your ranger has a scholar/alchemist slant.