Ah, villains — how we have loved and hated them all with the fervor of obsessed lovers denied one last kiss. The list of bad guys and girls who have terrorized the characters of “Hawaii Five-0” is varied and long, and at times some villains have outdone themselves on the evil meter. But the list of returning villains has been quite short. Since the demise of Wo Fat, played by Hawaii’s own Mark Dacascos, and Gabriel Waincroft, played by Christopher Sean, the attempts to fill the role of primary antagonist for the crime drama has been seriously lacking.

Ever since McGarrett killed Wo Fat in the 100th episode, “Ina Paha” (“If, Perhaps”), there have been other series villains — some better than others. Waincroft seemed to take over where Wo Fat left off, but after he died at the end of the sixth season the subsequent villains were milquetoast at best.

Yet, the ninth season presented a few strong options for a series villain. Several characters could return in the 10th season to rain down their cruelty and venomous ways on the team, as well as all of Hawaii.

THE CONTENDERS

There were a few bad guys and girls who stood out this season — Agent Greer (Rochelle Aytes), Omar Hassan (Ben Youcef) and his wife, Azra Hassan (Yasmin Dar), and Aaron Wright (Joey Lawrence), who returned after being introduced and captured in season eight.

We started the ninth season off with “Ka ʻowili ʻokaʻi” (“Cocoon”), a remake of the 1968 “Hawaii Five-O” episode “Cocoon.” Agent Greer is introduced and quickly revealed to be a traitor, yet it isn’t until “Ke kanaka i haʻule mai ka lewa mai” (“The Man Who Fell from the Sky”) when we learn why Greer has decided to betray McGarrett and her country. Still, we learn so much more about McGarrett’s ex-lover and why she not only betrayed him but also his entire SEAL team in subsequent episodes.

Greer sells the whereabouts of McGarrett, Joe White and their SEAL team to Omar Hassan, who sends a hit team after them. White and the rest of the team are killed prompting McGarrett and Catherine (Michelle Borth) to go after Greer in “Hala i ka ala hoʻi ʻole mai” (“Gone on the road from which there is no returning”). While Greer is guilty of several unforgivable acts — torturing McGarrett, killing White and his other SEAL brothers and betraying her country — Aytes never did rise to the occasion as a true villain. She just fell short as being a “good” baddie.

Greer is no longer a worry for McGarrett and the Five-0 team since Catherine had to kill her after Greer pulled a gun on McGarrett. Greer is the connection to another villain, Omar Hassan, the son of the target of the McGarrett’s SEAL team. Hassan wants revenge for his father’s death and McGarrett is the only one to survive his vengeance. Yet after McGarrett and Catherine — along with Danny (Scott Caan), Junior (Beulah Koale), Wade Gutches (David Keith) and Harry Langford (Chris Vance) find Hassan, McGarrett arrests him rather than avenging Joe’s death.

Yet, while Greer is dead and Hassan is in custody, it is Hassan’s wife, Azra, who sought revenge for her husband. In the season nine finale, Azra sneaked a ceramic gun into Five-0 headquarters with the aim to shoot McGarrett. We won’t find out if she succeeded until the next season, as the conclusion of the episode left us in a cliffhanger. But unless Danny or Lou (Chi McBride) shot Azra — she still could return as a villain.

LIKE A BAD PENNY

Wright seems to be the most likely villain to return, as he has done for the last two seasons. An expert hacker, Wright follows in the footsteps of his brother Ian (Nick Jonas), who terrorized Five-0 in the fourth season. Wright returned in the eighth season to release serial arsonist Jason Duclair (Randy Couture) from prison and escapes from Tani Ray (Meaghan Rath) while in custody.

Wright returned this season to get Five-0’s help after assassins kill all the members of the NSA listening station where he was putting his hacking skills to good use. The team blames him for the death of their good friend and former confidential informant Adam “Toast” Charles (Martin Starr) and for the torture of Five-0 ohana member Kamekona (Taylor Wily). His call for help turned out to be a ruse for him to steal cyber weapons from the government and sell them to the highest bidder — no matter if it starts World War III.

Really, Wright is the main contender for the role of series villain, and even though he might have been captured again by Five-0 — he has escaped before. Which of course, leaves the door wide open for another villain’s return.

Wendie Burbridge writes the “Five-0 Redux” and “Magnum Reloaded” blogs for staradvertiser.com. Follow her on Twitter and Instagram.