In this area, check out some of the special guests who initially appeared and were then re-cast in different roles in later seasons!  My favourite is that the perverted, sex maniac Mr. Penrose who initially starred as Chrissy's boss, later re-appeared as Janets dad in a later episode! Ha!

Ok - before we begin, I have to add this one in somewhere. In the Season 3 episode, Jack Moves Out, they had an actress named Janet Wood play as Frances. Now we already know that Janet Wood (the character) already lives in the apartment but they brought in another Janet Wood to the show. During the end credits, why is Janet Wood (the character), touching the name Janet Wood (the actress). Confused yet?

First appearing as Cindy's demanding boss, Mr. Hadley in the Season 5 episode "Jack to the Rescue" , then coming back in the season 6 episode called "Hearts and Flowers" as Mr. Franklin, Janet's Boss! How did his balding reverse in 1 year? Usually having too many jobs takes its' toll on you physically and not the opposite!

I'm sure she was thrilled to be cast for Three's Company, but when you're chosen both times to be a sleaze, you must wonder! First she plays an escort in "A Hundred Dollars a What", then returns in "An Affair to Forget" where she cheats on her husband with Jack! Naughty, Naughty!!

This one is tricky - could be the same dude as he's wearing a suit in both clips. In the first scene, he plays a high end waiter, but in a later episode, he turns into a pervert by pinching Janet's behind when she bends over in the flower shop! Thought i'd throw it in as the second pic is one of the creepiest smiles I've ever seen!

Oh, we're not done with this guy just yet! (Thanks to @thekidsin201). Here he's also hitting on Chrissy in "A Hundred Dollars A What?", then buys flowers for his wife, the ol' Bat in "Jack in the Flower Shop!". Did he lose his job as the Waiter at the swanky restaurant only to rebound as a telegram guy in "Father of the Bride?" So many unanswered questions that following him around would have made a great sitcom in itself!

This guy was crazy in any scene that he was in. First, he played the cheated on, bird talking, revenge seeking guy in the "Not So Great Imposterer, then he worked as the rough and tough Bartender in "Oh, Nun"

Perhaps the most famous double take is that Chrissy stars as the brunette walking down the bike path in the opening credits that puts Jack off balance!

The sex crazed Mr. Penrose (Chrissy's Boss) was later re-cast as Janets dad! Thank goodness Chrissy was no longer on the show at this stage otherwise, he may have chased her around the apartment!

Take away Mr. Angelino's beard and who do you have? You have the husband of a sex crazed woman, that's who!!!

This guy was badass in any scene that he returned for. First, he played Mr. Canon, the no-nonsense mafia man and then he returned cast as a jealous boyfriend who wants to kill Jack!

Once a creep, always a creep. First this character plays the role of a Guru/Predator on Chrissy and then returns as Janet's dance coach where he tries to take advantage of her as well!

First a doctor, then the father of one of Jack's girlfriends. In fairness, it could be the same character, however he went by 2 different names in both episodes.

First Jacks gets in trouble for getting a little too cozy with Roper's Niece and then she returns in a much later season as Mr. Angelino's daughter! Wait, if it's Roper's Niece and Mr. Angelino's daughter then that means that Mr. Roper and Mr. Angelino are...nevermind.

This guy must have paid a fortune for medical school. First as a psychiatrist then as Jacks dentist! Could it be that he even appeared a 3rd time on the show???

Yes! Our dentist + psychiatrist is also a crazy, love starved stalker! This time chasing Cindy's heart!

First this woman falls head over heels for Jack when he accidentally serenades her, and then she returns as another character in Janet's exercise class and she pays him no mind! Maybe she didn't like Jack's headband?

Even the wardrobe gets in on the double take action. Check out Jack and Larry both wearing the same top in different episodes. Larry wears it first in S6 E4 and then later Jack in S8 E6. Maybe Larry couldn't pay back the $50 he owed Jack, so Jack took the shirt as collateral? Photo Credit: Jordan Redding

The couch in Apartment 201 also first appeared on Maude ibn 1975, then on Sanford and Son (with orange pillow and all!) in 1976 before becoming a staple on the Three's Company set.