Who’s THAT girl? Sitcom star, 86, sparks firestorm of plastic surgery speculation with recent Instagram posts displaying very striking looks

A certain iconic sitcom star's recent Instagram posts have made fans very suspicious of possible plastic surgery that they say has made the actress “unrecognizable.”

The 86-year-old actress was born in Detroit, Michigan, to her Lebanese-American father and Sicilian-American mother.

She later moved to Beverly Hills, California, and attended Marymount High School before graduating from the University of Southern California with a teaching degree.

Her career path took a turn when she started acting in television programs in 1960, before getting her big break five years later in the London production of Neil Simon's Barefoot in the Park.

The now unrecognizable star was once a familiar face after landing the lead role in ABC's hit 1960s sitcom That Girl.

The now unrecognizable star was once a familiar face after landing the lead role in ABC's hit 1960s sitcom That Girl

The 86-year-old has built up a large fan base over the years and regularly shares photos and videos on Instagram with her 134,000 followers. However, recent reports have sparked speculation about the star's possible plastic surgery procedures

Marlo Thomas played Ann Marie, a beautiful up-and-coming actress, on That Girl from 1966 to 1971, producing 136 episodes of the widely beloved TV show.

She co-starred with Ted Bessell, who played her writer boyfriend on the show.

The actress decided to end her time on the show in 1971 and ABC wanted to end the series finale with a wedding between the two main characters, but Thomas declined, saying this sent the wrong message to her female audience.

Thomas claimed that ending the show with a wedding for women would indicate that the only possible happy ending is marriage.

Since her time on the show, Thomas has appeared in many TV shows, films and Broadway productions.

She is an outspoken feminist and founder of the Ms. Foundation for Women and creator of the women's website MarloThomas.com.

Thomas has taken home four Emmy Awards, a Golden Globe and a Grammy Award.

She has been married to former talk show king Phil Donahue since 1980 and is a stepmother to his five children.

The 86-year-old has built up a large fan base over the years and regularly shares photos and videos on Instagram with her 134,000 followers.

However, recent reports have sparked speculation about the star's possible plastic surgery procedures.

In a three-week video uploaded of Thomas getting ready to appear on the Today Show, users pointed out her “terrifying” qualities in the comments.

Marlo Thomas played Ann Marie, a beautiful up-and-coming actress, on That Girl from 1966 to 1971, producing 136 episodes of the widely beloved TV show. She is pictured at a Hollywood dinner with Henry Kissinger in 1970

Although fans have talked about the work Thomas may have undergone to change her appearance, the star herself has never confirmed any suspicions

Thomas is pictured with her husband Phil Donahue in New York City in 2014

The couple is pictured here at the 1996 Emmy Awards in Pasadena, California

Another photo of Thomas and Donahue shows them together in 1985 – at the height of Donahue's chat show fame

One user said: 'What the hell happened to her?'

'Why did she do that. She was such a beautiful woman. Why do women do this to themselves so shamefully,” another user commented.

Someone else said: 'How sad to work in an industry where you feel like you have to do so much work that you are unrecognizable! So very sad.'

Her followers agreed that she looked very different: 'Omg I had no idea who this person was! I will NEVER understand why people do this to themselves. It's horrible. And the doctors should be ashamed of themselves.”

Another said: 'I only recognized her by her voice.'

Not all comments were negative, with one user saying: 'Oh, to be so gorgeous at 85!'

Other viewers speculated that the video could have been edited: “I honestly thought it was done with Photoshop somehow… why would someone deliberately do that to themselves?”

Although fans have talked about the work Thomas may have undergone to change her appearance, the star herself has never confirmed any suspicions.

People have suggested that Thomas may have had a rhinoplasty, a facelift, and other types of Botox and filler treatments.