This character is a tribute to the American thrash metal band from California with the similar name Slayer. To unlock Sleigher choose one of the new Christmas Characters (Shooty Feet, Elfabear, Blitzen, Ho-Ho-Hobot, Hoppy Holiday, Poley) and defeat every Christmas enemy occurring in one round including the Christmas Boss.
It may also be possible that you need to beat round about 3 christmas bosses in different rounds.
#11 Glazed Ham Solo
This character is a tribute to the Star Wars Character Han Solo. To unlock Glazed Ham Solo you have to play with the secret Character Toy Roboto Jr. and collect the content in the wooden boxes. This is exactly the same unlock condition you need to unlock Toy Roboto Jr.
#10 Toy Roboto Jr.
To unlock Toy Robot Jr. you have to play Ho-Ho-Hobot, a new Chrismas character. Collect a certain amount of wooden boxes (round about 7). In those wooden boxes there are parts of the secret Character Toy Robot Jr.
#9 Roddy Cat
To unlock Roddy Cat play with Rowdy Cat and shoot down at least 50 Shopping Carts.
#8 Monster Savings
The official conditions reported by the developers for unlocking Monster Savings:
Collect at least 500 coins with Bargain Hunter in game. You don't have to collect the coins in one run.
We tried to unlock the character with that conditions, but we were not successful on iOS, but it worked on Android. Most probably there is a bug in the current version. The developers are informed and are working on it.
#7 Zombie Kitty
Play as the very first and basic character Shooty Cat, at one point the boss announcement "It's shambling this way will appear and a Halloween boss character will approach you. Then you have to just crash into this character and Zombie Kitty will be unlocked!
First of all unlock all new 6 regular Halloween characters Frankie, Flying Dutchman, Ghost Smoosher, Werewolfgang, Wanda, Vlad. Play each one of them and once you die Morty will be unlocked!
#5 Drama Llama
First of all unlock Hooty and Blobby. Now you have to get a good or a great score with both of the two characters. A great score is considered to be a high score or a score relatively near your highscore. Once you got it with both characters Drama Llama will be unlocked! This is considered to be "old people's music joke", because there is a 90's music band called Hooty and the Blowfish.
Play the game and find the Rainbow Cat in the tv shooting rainbow blocks, once you beat this character and die the Sparkles will be unlocked! It is very likely that you can play as any character. Sparkles is a fancy one, so check out its gameplay!