Over the course of Mortal Kombat's 20 plus year history, there have been many characters who've took part in the ongoing battle between Earthrealm, Outworld, and Netherealm. It's hard to argue against there being some classic characters that have entered the world of popular culture. However, there's also been a large amount of characters that failed to grasp on. Whether it was because of questionable character design choices, or them feeling like rehashes of older characters not in that particular installment.

When it comes to introducing new characters into the Mortal Kombat universe, there's a few factors that I feel weigh heavily on the longevity of the character in the franchise. One is the characters place and importance to the overarching mythos of Mortal Kombat, and interesting, unique character design. A new character can be weak in one instance, but if he's strong in the other, they can be rehabilitated in future entries.

The success of character development was strongest in the series in it's first three entries, and severely tapered off in the first 3D games in the entries. This can be demonstrated by a quick look at the characters introduced in each entry of the series, and how many games they appeared in. Armageddon was not taken into account, due to every character from MK1 to Deception was included, even those Ed Boon stated he hated (such a Hsu Hao and Drahmin). Also, I've tried to stick to only including games they were playable in, as opposed to just be hidden characters that players fought (like Reptile in Mortal Kombat).

Introduced in Mortal Kombat I:

• Johnny Cage (6 Games)
• Liu Kang (8 Games)
• Sub-Zero (8 Games)
• Scorpion (8 Games)
• Raiden (7 Games)
• Sonya Blade (6 Games)
• Kano (5 Games)
• Goro (4 Games)
• Shang Tsung (5 Games)

Introduced in Mortal Kombat II:

• Baraka (4 Games)
• Jax (6 Games)
• Kitana (6 Games)
• Mileena (6 Games)
• Kung Lao (6 Games)
• Reptile (6 Games)

Introduced in Mortal Kombat 3/Ultimate Mortal Kombat 3:

• Cyrax (4 Games)
• Kabal (3 Games)
• Nightwolf (3 Games)
• Sektor (3 Games)
• Sheeva (2 Games)
• Sindel (3 Games)
• Stryker (2 Games)
• Jade (3 Games)
• Smoke (3 Games)
• Ermac (4 Games)
• Rain (2 Games)
• Noob Saibot (5 Games)

Introduced in Mortal Kombat 4/Mortal Kombat Gold:

• Fujin (1 Game)
• Jarek (1 Game)
• Kai (1 Game)
• Reiko (1 Game)
• Quan Chi (4 Games)
• Shinnok (2 Games)
• Tanya (3 Games)

Introduced in Deadly Alliance/Tournament Edition:

• Bo'Rai Cho (2 Games)
• Drahmin (1 Game)
• Frost (1 Game)
• Hsu Hao (1 Game)
• Kenshi (4 Games)
• Li Mei (2 Games)
• Mavado (1 Game)
• Nitara (1 Game)
• Sareena (1 Game)

Introduced in Deception:

• Ashrah (1 Game)
• Dairou (1 Game)
• Darrius (1 Game)
• Havik (1 Game)
• Hotaru (1 Game)
• Kira (1 Game)
• Kobra (1 Game)
• Onaga (1 Game)
• Shujinko (1 Game)

Introduced in Armageddon:

• Taven (1 Game)
• Daegon (1 Game)

Introduced in Mortal Kombat X:

• Cassie Cage
• D'Vorah
• Erron Black
• Ferra/Torr
• Jacqui Briggs
• Kotal Kahn
• Kung Jin
• Takeda Takahashi
• Tremor

During the course of the first three games in the series, 27 characters were introduced and all 27 were featured in following installments. Between Mortal Kombat 4/Gold and Armageddon, 26 new characters were brought into the Mortal Kombat universe, however only six ever appeared in another game. Breaking it down, it becomes a little more interesting.

The characters between Mortal Kombat and Mortal Kombat 3 were woven and tied together in the mythos of the series. You had stories such as the battle between Sub-Zero and Scorpion due to their clans of the Lin Kuei and Shirai Ryu respectively, the later cyborg plans of the Lin Kuei with Cyrax and Sektor, Sonya Blade's feud with Kano and the Black Dragon. Even the weakest from a design point of view had a thread into the story behind the world that.

After taking the series into the world of 3D, the design took a nose dive. Many of the characters' designs were poor or lacked imagination, or were saddled with rehashed move sets from classic characters that weren't in those particular games. It didn't help matters that the ties to the universe were extremely weak for most, and didn't go past "This guy was friends/knows this guy from the earlier games". There are some instances where new factions were introduced, such as Daegon's Red Dragon Syndicate, as well as new intertwined backstories, like Dairou and Darrius.

While this was actually a very solid idea, and was a welcome shot at injecting new blood into the series, the characters themselves were just extremely lacking themselves. It is no surprise when you look at the most successful characters from between 4/Gold and Armageddon their stories were based deeply into the original mythos, such as Quan Chi, Shinnok, and Kenshi. The rest suffered from the two basic pillars of success in the series, place in Mortal Kombat Mythos and Character Design.

In 2011, the series was completely rebooted with Mortal Kombat. It truly is a great opportunity in that it gives characters that were poorly brought about in earlier games that failed, but still have great potential, a chance to essentially be repackaged. There are a few who come to mind that could turn out to be successful if brought back with unique move sets and new interesting designs. Namely, Daegon, Mavado, Reiko, Jarek, Sareena, and Frost.

Giving Daegon, Mavado and Jarek proper movesets and improved designs would allow another member of the Black Dragon Syndicate as well as a new faction with the failed Red Dragons from Deadly Alliance (forget Hsu Hao, there's nothing redeeming for him, and he's on record as one of Boon's most disliked characters). Sareena and Frost would allow for additional fleshing out of the popular Lin Kuei faction.

Reiko is a character that has always had untapped potential that was dragged down by a boring (and that's being generous) outfit in MK4 and an ending that eventually turned him into a joke. The ending to his story originally had him putting on Shao Kahn's helmet after going through a portal. This led to a discussion and theories about him being Shao Kahn, which Netherrealm addressing it by having him just saying he likes to wear Shao Kahn's helmet at night. It's a shame, because his appearance in Armageddon was a vast improvement. Give the proper treatment, he could very well be an important, powerful player in the world of Mortal Kombat as a general or person of power in Outworld.

The new characters that were designed for Mortal Kombat X are the most intriguing batch since Mortal Kombat 3. The personalities and designs are refreshing and unique, and they're tied into the backstory of the world well. It will be interesting to see how many are brought back in any future sequels, but it would not be surprising to see most of them get a part as series regulars.