When Agents of S.H.I.E.L.D. Season Two premieres this fall, viewers should expect to see new characters added to the cast. Fans will be pleased to see the addition of Marvel's lesser known characters as well. The show will premiere on ABC on Tuesday Sept. 23 at 9pm EST.

Here is a guide that will briefly explore the mythology and the actors behind the characters:

Barbara Morse, alias "Mockingbird"

At San Diego Comic-Con last week, a special Agents of S.H.I.E.L.D. panel confirmed that longtime Marvel superheroine Mockingbird will appear in Season 2. This news should excite fans, considering that this is Mockingbird's first live-action appearance in history.

In the Marvel comics, Barbara "Bobbi" Morse is a S.H.I.E.L.D. agent who is injected with the Super Soldier Serum. Incidentally, she was once a scientist working on Project: Gladiator that sought to replicate the serum. Peers call Bobbi the "Mockingbird" due to her habit of mocking enemies while in battle.

Mockingbird is a skilled fighter adept in acrobatic agility and hand-to-hand combat. Due to her scientific background, she is also quite intelligent and has a PhD in Biology. In the field, she dispatches her opponents with a pair of steel poles.

It will be interesting to see how she appears in the TV show, considering that her comic book appearances have seen many changes over the years. ABC has yet to confirm the actress who will star as the Mockingbird.

UPDATE: On Tuesday, Aug. 19, ABC confirmed that actress Adrianne Palicki has been chosen to star as Mockingbird in the upcoming season.

Isabelle Hartley (Lucy Lawless)

Actress Lucy Lawless will play Isabelle Hartley, an experienced S.H.I.E.L.D. agent who is good with knives.

Like Agent Phil Coulson (Clark Clegg), Hartley did not exist in the original Marvel comics that inspired the TV show. Instead, she is being introduced to the ABC series as never-before-seen character.

Given time, Agent Hartley may endear herself to fans the same way Agent Coulson did in the Marvel film franchise. Naturally, that depends on whether or not Hartley is killed off in second season.

It will be interesting to see how Lucy Lawless approaches this new character. Though she is better known for her leading-role in Xena: Princess Warrior, Lawless has starred in many shows that include Spartacus, Parks and Recreation, and Battlestar Galactica (re-imagined). So, Lawless is a welcome addition to the series.

Lance Hunter (Nick Blood)

Lance Hunter is yet another British character who is coming to Agents of S.H.I.E.L.D. Season 2. In Marvel comics, he is the head the head of S.T.R.I.K.E., which is seen as British equivalent to the S.H.I.E.L.D. organization. Hunter has often assisted Nick Fury and Captain America in past missions. The spymaster returns to being a naval commodore after his agency is disbanded.

Hunter is not the only Agents of S.H.I.E.L.D. character based out of the United Kingdom. The previous season saw the introduction of brilliant-but-zany scientific duo, Leo Fitz (Iain De Caestecker) and Jemma Simmons (Elizabeth Henstridge).

British actor Nick Blood will star as Lance Hunter. Due to Blood's age, 32, it is obvious that showrunners are re-imagining the character. Instead of an aged gentleman, Lance Hunter will be a mercenary that Agent Coulson recruits.

Daniel Whitehall (Reed Diamond), alias "Kraken"

Known in Marvel lore as a HYDRA founding father, Daniel Whitehall is a master manipulator who has the ability to change personalities in people to suit his purposes. Dubbed the Kraken, he is often depicted as wearing a high-tech armored suit that covers his entire body and part of his face.

Whitehall began his career in British intelligence in the early days of the Cold War, but later joins former-Nazi officer Baron Wolfgang von Strucker. Together they formed HYRDRA. At one part, Kraken ran a girls' orphanage where he experimented on children to create super assassins.

At Comic-Con, ABC announced that actor Reed Diamond will star as Kraken in the upcoming season. Diamond is best known for his recurring performance in 24, Homicide: Life on the Street, and Dollhouse.

Bakshi (Simon Kassianides)

Recently, ABC has invited yet another British actor on the show. On July 29, Deadline Hollywood reported that Simon Kassianides will star as Bakshi, "a confident right-hand man who's not afraid to do the dirty work."

Kassianides has appeared in the James Bond film Quantum of Solace. The report did give further details about Bakshi, who is a new character created for Agents of S.H.I.E.L.D. As such, viewers will have to wait for more information from ABC to know more about this mystery character.