Spooky, scary skeletons might send shivers down your spine, but the stars of the Hologic WTA Tour were the ones who served up tricks and treats in equal measure this Halloween. 

You might've heard how World No.2 Ons Jabeur pulled off a perfect prank on No.1 Iga Swiatek to kick off the WTA Finals Forth Worth with a fright between friends, but two of the event's other stars -- doubles players Desirae Krawczyk and Giuliana Olmos -- also weren't shy about getting in on the action.

Halloween Havoc: Jabeur pranks Swiatek at WTA Finals

Clad in blow-up animal outfits -- Krawczyk as a koala and Olmos as a dinosaur -- the two made Fort Worth's Dickies Arena their own personal zoo, chasing down Swiatek in the gym and Caroline Garcia on the practice courts.

Take cover! Animal planet invades the WTA Finals

The pair's hijinks were a hit on social media, eliciting kudos from not only fellow Fort Worth participants Coco Gauff and Jessica Pegula, but current and former American players Asia Muhammad and Kristie Ahn. 

"[A] better love story than Twilight," former WTA Players' Council member Ahn quipped on Krawczyk's post of the two.

Speaking of Gauff, the American teenager showed off not one, but two costumes on the eve of her Finals debut. A noted fan of both, the Marvel and DC comic book-to-screen universes, Gauff showed off her best cosplay as Raven and Moon Knight, two superheroes from those respective franchises. 

No doubt impressed with her commitment to both looks even as she prepares to be the youngest competitor at the WTA Finals since 2005, Gauff's good friend, ATP player Chris Eubanks, asked the question on everyone's minds in the comments of the teenager's Instagram posts: "Bruh how many costumes do you have?!?!?!"

There was also spooky fun to be had away from the Finals: Playing the WTA 125 Series event in Midland, Michigan this week, 2014 Wimbledon finalist Eugenie Bouchard served an ace with her rendition of the famous character Chucky, the evil doll of his own eponymous movie franchise.

Elsewhere, WTA legend Martina Navratilova's showed off intricate, full-face skull makeup that would've no doubt been the envy of all at the Halloween party she attended. 

But what's Halloween without candy? We'll return to Fort Worth to sign off: Stopping by the Tennis Channel desk after their opening round-robin wins, Barbora Krejcikova, Katerina Siniakova and Maria Sakkari all had the right idea.

Sakkari overcomes Pegula in WTA Finals opener