Werewolf: At first glance, this werewolf is very similar to previously produced wolfmen, but this one has a new touch: a bushy tail that attaches between the torso and legs. For GMs of D&D and Pathfinder games, werewolves (along with Wolf Tribe characters from the Legends of Chima theme) also make excellent gnolls.
Zombie Pirate: It's easy enough to make a zombie pirate out of other minifigures, and the old Pirates of the Caribbean sets included a number of undead sailors. But this one is an excellent blend of the more cartoony aesthetics of the Pirates and Monster Hunters lines. It's one of my personal must-haves in this series, because I run a campaign set in Freeport: The City of Adventure, which has plenty of ghost ships.
Crazy Scientist: One of the previous Minifigures series included a mad scientist, but this one has obviously been experimenting upon himself: his cranium has expanded to fit his enlarged brain. This makes him excellent for use as a comic-book mutant supervillian. Unlike older beaker props, his is the first with opaque contents, and has a fly printed on the side--he's clearly the creator of the Fly Monster, below.
Wacky Witch: The Minifigures line has offered a witch before, too, but this one is goofier looking, with a ragged, bright purple dress and striped stockings. I vastly prefer the earlier, scarier hag (which was modeled after the Wicked Witch of the West). The pouty-looking black cat is the best part of the new one.
Plant Monster: The plant monster is still consuming its last victim, whose frightened face peeks out of its mouth. If you want to make it a little less silly-looking, replace the minifigure head with one of a solid color--preferably black or red--or with a 1x1 cylinder brick. This makes the mouth look more maw-like. (The mostly-teeth head from an Atlantis Hammerhead minifigure works even better.)
Fly Monster: This character is easily the most freakish member of Series 14: a winged humanoid with a large insect's head, and one hand mutated into a pincer-like claw. It also has a very different look from previous bug-like LEGO minifigures such as the aliens from Galaxy Squad and the scorpion and spider tribes from Legends of Chima. It's perfect for the retro B-movie horror look of this series.
Specter: This character and the Banshee, below, use the same ectoplasmic lower-body piece that was first used for some of the ghostly villains in the latest Ninjago storyline, but in new colors. The Specter is a lovely ghost figure, except that his derpy face doesn't inspire much fear. That can easily be fixed by replacing the head with a different face, such a skeleton's, or a blank black head for a hollow look. (Even turning the white head around to the blank side would make him more menacing.)
Zombie Cheerleader: This character is cute, and delightfully cheerful for a rotting corpse. Apart from the head, though, she isn't much use as a RPG miniature except for modern-day games,
Tiger Woman: This figure has tiger stripes painted on her legs, arms, front, and back, as well as on the hard-rubber tail that attaches at the waist. She's perfect for a weretiger, rakasta, or catfolk, or an anime catgirl. The smirk and the whip give her a ton of attitude, too.
Gargoyle: This gargoyle has the classic horns, fangs, and bat-wings associated with his type, allowing him to be used as a D&D-style gargoyle, imp, or other devil. Substitute normal-sized gray legs to give him a more imposing stature, or remove the wings and headpiece to make an animated stone statue or golem. The wings are perfect for a tiefling or succubus, or can be used to turn a Lizard Guy, Ninjago serpent, or Chima Crocodile Tribe character into a man-sized winged dragon. These many alternate uses for his elements make the gargoyle the most versatile entry in this series.
Skeleton Guy: It seems to be a tradition that every Minifigure series includes one character in a Halloween costume, and this set is no exception: this is a normal guy wearing a skeleton costume. The paint job faithfully copies a LEGO skeleton over all four sides of the body, This figure could be repurposed as a skeletal ghost, or a body that hasn't completed lost all of its flesh. However, it would probably serve best for a cultist of a death god, who is trying to look more like one of the undead he reveres.
Monster Rocker: This figure is my least favorite in the series. He's simply a Frankenstein's monster--the third or fourth version of such that LEGO has produced--with a guitar and a lot of denim.
Zombie Businessman: Like the cheerleader, this character is of limited use as a miniature outside of modern-day games. (He'll probably end up haunting my cube at work instead.) His mussed hair is the easiest element to reuse.
Banshee: This character was easily the one that I (and my two children) wanted most, The Banshee is a beautiful ghost figure, with a translucent hair piece (a first!) that complements her transparent lower body quite nicely.
Square Foot: This version of Bigfoot is identical to the earlier Yeti minifigure, but with a new color scheme and a change of props. He would serve well as a sasquatch, ape, or bugbear.
Spider Lady: This woman is clearly a vampire, but with a spider fetish instead of the classical bat theme. She comes with a clear plastic, two-piece cape and a beehive hairdo, giving her an Elvira: Mistress of the Dark vibe. Her outfit, with its web patterns and spiders, just begs to be used as the base of a drow noble or priestess character.
Overall, Series 14 is extremely satisfying. Every series will have a few characters I don't care for, but this set has very few (two or three at most) that I'm indifferent to. My personal favorites are the Plant Monster, Tiger Woman, Gargoyle, Banshee, and Spider Lady.