Stranger Things fans are just noticing one major character was missing from final season

It's been about a week since Stranger Things treated us to its very last episode on New Year's Eve (31 December).

The final episode left many Netflix users scratching their heads as they rushed online to share a load of fan theories about possible meanings. The latest buzz online saw Stranger Things viewers only now just noticing that one major character was missing from the fifth season.

The character in question is none other than Max's mum, Susan Hargrove, portrayed by actress Jennifer Marshall, a recurring character known for her strained relationships with Max and her late stepson Billy, as well as her frequent absence, which is often attributed to her working multiple jobs.

After losing Billy and facing the near-death of her daughter, Max, viewers would unsurprisingly expect Mrs Mayfield to be a constant and grieving presence at the hospital.

Instead, the character seemed to vanish entirely, leaving Max’s pals to handle the emotional heavy lifting themselves.

Stranger Things fans are just clocking that Max's mum, Susan Hargrove, was nowhere to be seen in the final season (Netflix)

Last week, Marshall herself took to Instagram to share a series of behind-the-scenes and on-screen snaps with the first's overlay text reading: "But where was Max's mom? Give your theories below... best ones get reposted!"

She added in the caption: "Okay folks! It’s over…but where was she? What kind of mother isn’t there for her child while she’s in the hospital? Give me all your theories…"

After catching light of the snap, an avalanche of sci-fi fans couldn't wait to share their many theories, including 'working like 200 jobs to pay for Max’s medical bills' and 'alcoholism'.

Many viewers, however, were convinced her absence in the final season was simply up to the fans to decide.

Actress Jennifer Marshall asked fans what their theories were regarding her absense (Instagram/@jenn13jenn13)

One X user penned: "She visited Max off-screen."

"Yeah, we can IMPLY that," quipped a second while a third chimed in: "Another plot hole. The fans have to decide."

A fourth agreed: "She left it for the viewers to decide where she was."

"But it is open to interpretation," echoed another.

And a final X user added: "Best off-screen parenting I have ever seen!"

On the subject of leaving things up to interpretation, the Duffer Brothers, who created the hit series, also left it up to viewers to decide what they think happens to protagonist Eleven, played by Millie Bobby Brown.

"She lives on in their hearts, whether that’s real or not," writer and producer Ross Duffer told Tudum.

Stranger Things is currently available to stream on Netflix.