Here's why Tom Felton exited The Flash after only appearing in season 3 - and if he would ever return. Before his breakthrough role as Draco Malfoy in the Harry Potter franchise, Felton had appeared in movies like The Borrowers and Anna And The King. Of course, he's still best known for playing Malfoy, but since that franchise came to an end with Harry Potter and the Deathly Hallows – Part 2, he's branched out into many different projects. He played another villain in the sci-fi reboot Rise Of The Planet Of The Apes - where he's partly responsible for the titular uprising - in addition to appearances in horror movie The Apparition or historical drama Belle.
In 2016, Tom Felton joined the cast of The CW's hit superhero series The Flash during its third season. Felton played Dr. Julian Albert, who became Barry's new CSI lab partner and an ally to Team Flash. During his run on the show, Felton's Albert is revealed to be - unknowingly - a villain named Alchemy, voiced by Saw star Tobin Bell. Albert also formed a connection to Caitlin Snow after he was freed from his alter-ego, and while The Flash season 3 isn't considered one of the show's strongest, Felton's work was well-received.
Despite this, The Flash season 4 revealed that Dr. Albert had moved back to London, and outside of some mentions in later seasons, the actor has yet to reappear in the series. While some viewers were disappointed to see Tom Felton exit after The Flash season 3, there was no drama involved in his exit. The actor revealed to Digital Spy in 2018 that he only signed on to The Flash for one season and when that came to an end, Felton left to work on other projects such as action movie Stratton and YouTube sci-fi series Origin, which was canned after one season.
Felton stated in the same interview that he'd be more than open to a future return, stating he missed working with the cast and that "I had a great time there in Vancouver for nine months. Yeah, I say bring back Julian!" There's been no more word on Albert returning, however, and the character's exit from The Flash felt a little unsatisfying and abrupt.
The odds are good that before The Flash comes to a close, Tom Felton's Julian Albert will make some kind of return appearance, even for just a cameo. In the meantime, Felton hasn't been hurting for work, appearing in the likes of A Babysitter's Guide to Monster Hunting and 2022's Harry Potter 20th Anniversary: Return to Hogwarts.