Aso ni San Roque

• Mona Louise Rey as Fatima Salvador / Raquel[2]

A blind girl with a golden heart who is the offspring of a mortal and a manananggal. Behind her persona is a prophecy that destined her to end the dark forces that plaguing the human race. Because of this mission, her life is now in danger as the legions of darkness are lurking to kill her to prevent her from fulfilling the prophecy.[2]

• Princess the dog as Anghel

St. Roch's dog who came to life to be Fatima's guide through her quests and battles to defeat the evil forces.[3]

• LJ Reyes as Lualhati Salvador / Lourdes

Mateo's great love. Lourdes is a beautiful and kind-hearted young lady. But behind this beautiful persona concealed a dark secret—she belongs to a family of manananggal, but the reluctant one. This revelation altered the love Lourdes and Mateo hoped to share together for life. This dim chapter in Lourdes' life turns into a joy as she gives birth to Mateo's child—a beautiful baby girl she named Fatima. But another tragic twist of fate unwittingly leads Lourdes apart from her baby.[4][5]

• TJ Trinidad as Police C/Insp. Mateo Salvador

A righteous, very principled and reliable policeman with a scarred past—one that continues to haunt him till this very day. In the wake of his doomed romance with Lourdes, Mateo vows vengeance on the whole manananggal race, completely unaware that Lourdes is carrying his child. Years passed. In an unexpected turn of events, he cross paths with a blind beggar named Fatima and eventually became attached to her, unaware of their real connection.[6]

• Pen Medina as Ben "Mother Ben" Asino

An old gay man who happens to be under the control of a syndicate. Loud and unconventional. He is a merry deviant in a cheerless world of misery and tears. He adopts Fatima and from then on, he became the sole protector of the poor, blind little girl.[7]

• Eddie Garcia as Supremo

The powerful head of all aswangs. Though he acknowledges the age-old adage that good will always triumph over evil, this does not prevent him from trying to make a difference. His mission is to spread evilness to mankind, to conquer the earth and make it his kingdom and to kill the blessed child, Fatima.[8]

• Gardo Versoza as Kanlaon

The king of the "aswang ng hangin" or the winged-vampires, better known in Philippine mythology as manananggal. He goes to great length to find and kill Fatima to prevent her from fulfilling the prophecy.[9]

• Angelika Dela Cruz as Bulan

An evil witch, who also ruled as the queen of the "aswang ng apoy" or the fire-powered witches. In the real world, she is known as the ruthless and fearless head of a syndicate involved in child trafficking and where Mother Ben and Fatima work. Legend has it that Bulan was once a goodhearted person, but the tragic death of her beloved husband and son led her to embraced evilness. She is the traitor to aswang's by not listening to Supremo.

• Gwen Zamora as Anaira

An evil mermaid who also ruled as the queen of the "aswang ng tubig" or the sea-based evil creatures. She preys on fishermen by using her mesmerizing beauty and charm. Anaira apparently has a soft spot for children, converting them into her minions whenever possible. This makes her the least motivated at hunting down the prophesied child. She now seeks to become Fatima's surrogate mother, unaware that she is the very child her brethren seeks to eliminate.[10] Because of that soft spot her human heart and mind has a conscience and still has good in her heart.

• Paolo Contis as Sento / Peter Silverio

The leader of the "aswang ng lupa" or the land-based aswangs. In his past life, he was Peter Silverio, a wealthy and popular equestrian who sold his soul to the devil to regain his strength and to have eternal life. Using his strength and fast ability, he preys on people that's cross his paths, most commonly virgin women and lost travelers.[11][12]

• Rich Asuncion as Bernice Montemayor

An ambitious, aggressive and tough TV reporter/journalist. She is so focused and she would do everything to attain her goals and would do everything for the man she loves—Mateo.[13] Although not intentionally she led Bulan and Sento to Fatima before she can get to Mateo and in the process she became a mixture of n aswang of lupa and apoy by them.

• Eddie Garcia as Police Director Danilo P. Aragon

The husband of Doña Constancia and the brave and principled head of "Task Force Kababalaghan" or the paranormal division of National Police. His son was killed by the aswang and vows to take revenge on them.

• Boots Anson-Roa as Doña Constancia Aragon

The wife of Director General Danilo Aragon, a rich and strict woman who finds Fatima while wandering in the streets with her pet dog, Anghel. Upon learning that the girl is an orphan, Constancia takes her to her mansion to look after her.[14]

• Gene Padilla as SPO3 Paul Andrade

Mateo's bubbling, yet loyal, sidekick and fellow cop. Serves as the series' source of comic relief, he apparently suffers from an allergy to dogs; and because of that, he can tell whenever Angel the dog is within his vicinity, much to Mateo's convenience.

• Nova Villa as Ofelia Sandoval

The aunt of Mateo who also acts as his surrogate mother. Deeply religious and full of virtue. She also served as one of Mateo’s sources of comfort in his times of distress, and has some knowledge concerning the supernatural, such as the Tikbalang's weakness.

• Buboy Garovillo as Noah

A former clergyman who lost his mind after he witnessed the tragic death of his family.[15]

• Rafael Rosell as Anton Martinez
• Diva Montelaba as Ruka
• Ehra Madrigal as Lena Martinez
• Sherilyn Reyes-Tan as Diga
• Gerard Pizarras as Iwak
• Raquel Montesa as Anton's mother
• Ervic Vijandre as Robert Tolentino
• Ryza Cenon as Grace Santos
• Mariz Ricketts as Rosa Santiago
• Djanin Cruz as Zita Dizon
• Kiel Rodriguez as Timo Magno
• Roldan Aquino as General
• Miguel Tanfelix as Onyok
• Julian Marcus Trono as Joem
• Chinggay Riego as Oryang
• Mary Joy Gula as Kiting
• Barbara Miguel as Didi
• Elvis Gutierrez as Marcus

The cast was first presented during the series' story conference held on August 2, 2012 at GMA Network Center. Mona Louise Rey was chosen to play the role of Fatima, the protagonist. Rey, who rose in stardom after the successful drama series[21] Munting Heredera, felt overwhelmed with the network's support for her career and at the same time, excited for the role assigned on her.[22]

Meanwhile, Princess, a two-year-old half Golden Retriever and half Cocker Spaniel, was chosen to be part of the series as Anghel, San Roque's dog who defend and guide the main character through her adventures.[23] Don Michael Perez said, "Princess, is definitely born to be a star," he says. The dog's trainer Ergie Estrella said that he did not encounter difficulty in training the star dog, saying that all it takes is positive reinforcement.[24]

TJ Trinidad and LJ Reyes shared equally important roles in the series. Reyes considered this series as her biggest break ever. After being typecast in villain characters [she's associated in her villainous roles in Time of My Life[25] and The Good Daughter,[26] the network assigned her to play one of the main characters in the series, as birthmother of Mona Louise Rey's character.[27] In one of her interviews, Reyes said that it's her first time to play a mother role on TV but she doesn’t mind doing it as long as the story is good and the character, as well.[4] Meanwhile, Trinidad is all praise for his screen partner, said that Reyes is nice and very committed. "And I think, it’s gonna be a good partnership for the show and, you know, with the whole cast, story, and the script, it’s so exciting. Very fast-paced", he added.

The dark forces or the main antagonists of the story are portrayed by Angelika dela Cruz, Gardo Versoza, Gwen Zamora and Paolo Contis. Dela Cruz was cast as Bulan, an evil witch and the leader of the syndicate; Versoza playing Kanlaon, the king of the manananggals; Zamora playing the role of Anaira, an evil mermaid; while Contis playing the role of Sento, the leader of the tikbalangs.[28][29]

Rafael Rosell had a guest role in the series. He played Anton, the man who saved LJ Reyes' character from the wrath of manananggals. This served as his first project in GMA Network.[30]

Pen Medina was cast as mother Ben, an elderly gay and the adoptive parent to the lead character. Originally, the role was offered to Eddie Garcia but due to health concern,[31] Garcia later requested the producers to give him less time-demanding character. He portrayed the role of Supremo, instead.[32]