Television host, comedian, writer, producer and actor David Letterman has only two episodes of the Late Show with David Letterman left. He announced his retirement last year and will be replaced by comedian Stephen Colbert.

After over 35 years on television, Letterman has talked to numerous celebrities including Oprah Winfrey, Cher, Madonna, Lady Gaga, Bill Murray, Johnny Carson and many more.

Letterman became well known for his no-holds-barred interview style when it came to asking celebrities some of the toughest questions about their career. He also became a mediator as well as a counselor, always rooting for the best in people when they're struggling.

Letterman isn't new to controversy, getting a slap on the wrist for some comments he made on certain serious issues, but he was always able to bounce back and continue on for the long run.

In 2013, Letterman surpassed Johnny Carson as the longest running late-night talk show host. His final Late Show will take place May 20.

In honor of his long-running career, here are the Top 10 guest appearances on the Late Show with David Letterman.

image courtesy of Roger Wong/INFphoto.com

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10. Lindsay Lohan

This got awkward when Letterman brought Lohan on to talk about her struggles, but he later provided words of wisdom, hopes of a better future for her and praised her for her courage to come on the show despite his jokes towards her, causing her to tear up a little.

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9. Madonna

This awkward Madonna interview became one of the most memorable moments because of her swearing. She constantly dropped the F-bomb while smoking a cigar and telling Letterman how soft he got.

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8. Demi Moore

This was Demi Moore's appearance after her famous strip tease. She revealed her new look for her film G.I. Jane and saw the strip tease of her then husband Bruce Willis. Letterman gave Willis a call during the interview to talk about it.

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7. Howard Stern

Howard Stern appeared on the show to promote his book, Miss America. He appeared on the show in full drag along will freshly shaven legs and a manicure.

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6. Drew Barrymore

Drew Barrymore gave Letterman a surprise after jumping on his desk and flashing him. He didn't seem to mind.

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5. Sacha Baron Cohen

Sacha Baron Cohen appeared on the show as his character Borat. This may have been one of the most awkward interviews in Late Show history.

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4. Lady Gaga

Lady Gaga's appearance was a little off from the start. Everyone knew what a character she was, and her appearance on the show didn't alter anyone's assumptions of her character. It was a fun interview and Letterman made it funny during time's of awkwardness, but after she ate his notes, things got even stranger.

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3. Johnny Carson

This appearance marked legendary host Johnny Carson's last time on television. Carson hosted the Tonight Show for 30 years and appeared as a guest on Letterman, but instead took Letterman's seat. There weren't any words spoken in this interview, but it was such a memorable moment, that words weren't even needed.

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2. Oprah Winfrey

Oprah and Letterman's discussion quickly grew uncomfortable after the topic of race came up, which was then fallowed by personal relationship questions which Oprah appeared to be uncomfortable with. Even after a few boo's from the audience and a rumored feud, Oprah and Letterman have always stated that they were friends and everything else was just rumors. Oprah made her final appearance on The Late Show on May 15, 2015.

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1. Cher

This interview became one of the most memorable moments on the show when Cher called Letterman an a**hole. Cher shared her concerns with Letterman who handled the whole situation very well and while everyone thinks that Cher wouldn't be brought back, she made numerous appearances afterwards including some performances.