Name Drop: In "The Frickert Fracas", Maude Frickert tells Fred he looks like Glen Campbell.
In the New Scooby Doo Movies, a character almost always name-drops the celebrity guest(s) when they first meet them. (i.e., "Look, it's Jerry Reed!")
A name drop through tagline: In Scooby Doo Meets The Addams Family, Scooby's "I ate the whooooole thing!" referred to the tagline of an Alka-Seltzer commercial prominent at the time, which was "I can't believe I ate the whooooole thing!"
From "The Ghost Of The Red Baron" (with the Three Stooges) after the gang sees the Baron in his bi-plane:
Shaggy: I thought the Red Baron was a beagle.
Daphne: That's Snoopy, dummy!
In the comic book story "The Gorgeous Ghost" (Gold Key #25, April 1974), the boys and Scooby comment on Daphne after she is shined up for a beauty contest:
Never Say "Die": While some are less aware, this has changed throughout the franchise. In which case in the earliest season the gang are in real danger, but it is often not really spoken about directly. The only exceptions being when somebody had to die to set up the episode's villain. (as in the week's monster is the ghost of somebody)
Later incarnations that went for a Darker and Edgier atmosphere have on purpose tried to avert this a lot more as time goes on.
No Guy Wants to Be Chased: In Scooby Doo and Meets the Boo Brothers, Sadie Mae Scroggins, an attractive but aggressive teenage girl, is smitten with Shaggy, who spends as much time running from her as the ghost.
Could be construed as a StealthPun: Shaggy is constantly "chased" by ghosts that never catch him, where he is caught many times by a boy-crazy girl.
Occult Detective: Though the occult almost always turns out to be someone in a Halloween costume.
The Only Ones: Vincent Van Ghoul makes it clear that Scooby and Shaggy are the only ones who can get the 13 ghosts back into the chest of demons, because they're the ones who let them out.
Only One Plausible Suspect: Used frequently in various versions of the franchise. Subverted once in What's New, Scooby-Doo? though, in the episode "It's All Greek to Scooby". The crook turns out to be some random person the gang has never met before. Velma naturally is rather displeased and keeps insisting her theory about who was the monster was at least plausible.
Only Sane Man: or girl, in this case—Velma in Music Of The Vampire. Although she does get a strange snark in when Daphne disappears and it is learned that the vampire seeks a bride with "beauty and is pure of heart."
Velma: You know, I'm pure of heart. Does anyone ever think of kidnapping me?
Our Cryptids Are More Mysterious: While individual monsters in the franchise are often made up from scratch, several classic cryptids such as the Loch Ness Monster and the Chupacabra have featured in the animated movies or more recent programs.
Our Ghosts Are Different: From The 13 Ghosts of Scooby-Doo right down to the last ghost. While they are all referred to as ghosts, the series goes back and forth on whether they're actual demons or something else entirely. A couple of them even seem more like rival magic users to Van Ghoul rather than actual spirits.
Outdated Outfit: The gang's original 1969 outfits usually get copied, but a few adaptations give them fashion makeovers.
This is lampshaded in one of the made-for-TV movies. Fred is seen getting dressed, and he puts on the orange tie he wore in his original outfit. He thinks about it for a few seconds, then says "Naaah," and takes it off.
Lampshaded in Scooby Doo and the Cyber Chase where the gang meet digital models of themselves from years earlier, who are still wearing the original outfits. For most of the segment, it's the only way to visually tell the two groups apart. Fred also gives himself a comment on the ascot.
The two made-for-TV live-action obviously deviates a a little from the gang's appearances — Fred has dark hair. This is subverted and lampshaded in Curse Of The Lake Monster: Fred and Daphne pose as mannequins to lose the trail of the creature, and they are both done up as the original cartoon Fred and Daphne. After looking in a mirror, Fred thinks it's a good look. Daphne thinks he's being ridiculous.
The New Scooby Movies Addams Family episode did successfully lead to a Addams Family Cartoon.
Likewise with Batman on Thew New Scooby Movies lead to the Western Animation/Superfriends.
One episode of The Scooby Doo Show goes through a lot of trouble to introduce us to The Alex Super Experience and even features a new animal companion in a frog, this was either an aimed pilot or recycling of an unsold meddling kids show.
The last episode of Scooby and Scrappy Doo backseats Fred, Daphne and Velma, and has Scooby and Shaggy be rescued by Scrappy and two of his childhood friends. Seems very much a spinoff that didn't take.
Scrappy Doo and Yabba Doo was given a whole segment one season for this reason
On The 13 Ghosts of Scooby-Doo we also spend an episode introducing a variety of comic parody characters with spotlight on three different ones, very likely a candidate for a three short show
Put on a Bus: Every member of the gang, save for Shaggy and Scooby, received this treatment eventually.
Relationship Upgrade: Shaggy and Velma from the looks of it in the new series. Since scuttled as of episode 10, and as a result, Velma is mad at both Shaggy and Scooby.
Replaced the Theme Tune: The later seasons did away with its iconic "Where Are You?" theme song in its entirety. Many fans assert that this change coincided with an overall drop in the show's quality as it preceeded the introduction of The Original Scrappy by one season.
Robot Maid: Or Robot Butler, in this case: Robi in Shaggy & Scooby-Doo Get a Clue!.
Roger Rabbit Effect: On ABC's 1976 Saturday morning preview special (aired the evening before the new season started), Scooby appeared with a live action Jimmy Osmond. They both danced to the 1971 Osmonds confection "Yo-Yo."
A 1980 promo for ABC has Scooby entreating a live-action bored little boy to join the parade of ABC stars proceeding down the street of the kid's neighborhood.
Romantic False Lead: In the first few direct to tv movies, such as Zombie Island and The Witches Ghost, there would always be at least one character that Fred or Daphne would have a crush on, solely so that the other wound up being jealous and inducing Ship Tease.
In the movie Looney Tunes: Back in Action, Scooby and Shaggy are seen in a studio cafeteria threatening Matthew Lillard, who played Shaggy in the 2002 and 2004 live-action Scooby theatrical feature films (averted seven years later, when Lillard would assume Shaggy's voice on the cartoon).
Shaggy: What kind of performance do you call that? You made me sound like a total space cadet, man!
Matthew Lillard: I'm sorry you feel that way. I was just trying to be true to your character.
Shaggy: If you, like, goof up on me in the sequel, I'ma coming after ya!
Scooby: Reah. And Ri'll rive you a Scooby Snack! [growls viciously]
In "Curse of the Lake Monster" the jab about relationships in the end seems to be one directed towards Mystery Inc.
'70s Hair: Considering it was made about that time, it's not all that shocking.
Ship Tease: In the original show it seems to heavily lead this on Fred and Daphne. Shaggy and Velma to a lesser extent as in some cases it may also just be script left overs from when the two were conceived as brother and sister.
During the 80s however this shifted to Shaggy and Daphne when Fred and Velma weren't around. The most heaviest of this era being in The 13 Ghosts of Scooby-Doo where at one point they share a really long hug.
Starting with Zombie Island this was returned back to Fred and Daphne and in the series of dtv movies it becomes a quick plot point, but is shelved back at the end of the episode.
Spanner in the Works: Shaggy and Scooby act as this in Zombie Island; Samone and Lena dismiss them, and they end up disrupting the ritual long enough for the others to turn the tables.
Special Guest: Luminaries that appeared in cartoon form on the show: Jonathan Winters, Don Knotts, Phyllis Diller, Sandy Duncan, Sonny and Cher, Jerry Reed, Davy Jones, Tim Conway, Cass Elliot, and Dick Van Dyke. The Addams Family appearances re-recruited John Astin and Carolyn Jones as the voices of Gomez and Morticia. And Pugsley Addams was voiced by a young lady by the name of — you may have heard of her — Jodie Foster.
What's New, Scooby Doo? had guest appearances by hockey's Brett Hull, baseball's Mike Piazza, skateboarder Chris Krug, Steve Harwell of the group Smashmouth, and music group Simple Plan. Episode 11 of Scooby-Doo! Mystery Incorporated featured author Harlan Ellison.
Speech-Impaired Animal: Lampshaded in Scooby Doo and the Alien Invaders; Crystal and Amber [Shaggy and Scooby's love interests in that film] are revealed to be aliens at the end, and Amber, the dog, can talk.
According to studio bios from the cast we know, Fred and Shaggy are 17, Daphne is 16 and Velma is 15. A Pup Named Scooby-Doo would chronologically have Fred and Shaggy at age 10, Daphne at 9, and Velma (who in this series sleeps in a jumper) at 8.
Stalker with a Crush: In What's New, Scooby Doo?, Velma has one in the form of an inventor nerd named Gibby Norton.
In "Bravo Dooby Doo," Velma flirts with Johnny Bravo.
Velma: (winks to Johnny) I don't bite!
Johnny: (points to Daphne) Yeah...but does she?
In Scooby-Doo: Camp Scare, a ranger investigating the destruction of Camp Little Moose flirts with Velma, who is squicked.
The Stoner: Shaggy. Okay, so the show never actively says he's The Stoner but he's stick thin, scruffy, always hungry, will eat dog snacks, thinks his dog can talk (the others could be humoring him or are probably as wasted as he is), and he's always freaking out.
According to the show's creators, the idea that Shaggy did pot never even entered their heads in the creation of the character. But since it was brought up, a lot of the movies have a tendency to joke about it. And fans believe it.
Story Arc: Scooby Doo: Mystery Incorporated has one of these, with the mysterious Mister E sending them clues about their latest mystery and challenging them to solve the disappearance of a previous band of mystery-solving teens years ago.
Take the Wheel: In Monsters Unleashed, when the gang is being chased by the pterodactyl monster, Freddy asks Shaggy to take the wheel of the Mystery Machine while he tries to shoot the monster down. A little while later, Shaggy gets called to the back of the van so he can help Velma, and he leaves the driving to Scooby. To Scooby. Granted, he's pretty intelligent as far as animals go, but he's still not that far up the scale...
Tangled Family Tree: Each series/spinoff seems to insist on introducing (and, with few exceptions, never showing again) more and more relatives of the gang... cousins, uncles, aunts, grandparents, parents (Fred's and Shaggy's parents in Mystery Inc. are different than was previously presented), and in some spinoffs, even siblings. At this point, the Rogers, Dinkley, Blake, Jones and Doo family trees' must rival the (Mc)Duck family tree in complexity...
Taxman Takes the Winnings: This turned out to be the motive behind one of the Monster of the Week schemes. The perpetrators had discovered a sunken treasure, and were trying to smuggle it out without declaring it, because if they did Uncle Sam would come in and take more than half of it.
This was most likely comic book story "The Galleon Ghost" (Gold Key #2, June, 1970). The "ghosts" were actually gypsies who feared that the IRS would take it all, but Fred assured them that they would still be well off after Uncle Sam's take.
10-Minute Retirement: Happens twice. In the prime time special Scooby Goes Hollywood, he quits his Saturday morning show to pursue a career in nighttime TV. In the 13 Ghosts episode "It's a Wonderful Scoob", he becomes so traumatized by the episode's Big Bad that he goes back home to his parents. In the first instance, Fred, Daphne and Velma lead a rally for Scooby to return to his cartoon show. In the second, Vincent Van Ghoul shows Scooby the future world without him stopping the villain Time Slime.
There Are No Adults - They either don't have parents or their parents just don't care that their teens travel around the world solving mysteries with a talking dog.
While not directly approached in the original, Daphne's first relative is a famous director, hinted at her wealth. Later down the line the family trees have been extended so far it seems likely the Scooby Gang are all from affluent families. Only once do they seem to need money, and by the end of the episode (which is only a few nights later, it's no longer a concern).
Mystery Incorporated subverts this, with their parents appearing frequently to try to get them to stop solving mysteries, because in this world that's what rebellious teens do apparently. Except for Velma's mother who provides them with information on whatever monster concept the crook of the week is using and her father who only appears three times.
Unexpected Inheritance: In "A Night of Fright is No Delight" on Scooby-Doo, Where Are You! the plot centered around a Scooby getting the chance at inheriting an unexpected inheritance worth millions - which turned out to be millions in Confederate currency, which was worthless (clearly they never thought of selling all that Civil War memorabilia to museums or other collectors).
Unintentional Backup Plan: Common. Often the original trap that is set will not work, but Shaggy and Scooby's incompetence causes it to fail, but yields similar results.
Unspoken Plan Guarantee: In the older shows, Fred would often explain or demonstrate his ghost traps in detail before springing them - naturally they would typically fail, but also occasionally worked perfectly if he didn't explain it beforehand. In later series the plans failing bit itself became more iconic than the set-up, so the traps would backfire regardless of whether he explains them or not.
Vague Age: The Mystery Gang. They're only described as "Meddling Kids," but considering how much time they spend on the road, they almost certainly have to be in their 20s, or late teens at the youngest.
Their ages have been given, for the original series at least. Velma is fifteen, Daphne is sixteen, and the boys are seventeen. The original premise was to have them be a teen rock group on tour, which makes the lack of parents and time on the road more explainable.
Verbal Tic: Like, Shaggy, obviously. Also of note, Professor Flakey in 1972's "The Caped Crusader Caper", one of two crossovers with Batman and Robin. Flakey's dialogue consists almost exclusively of spoonerisms and this memorable malapropism:
Flakey: I always liked Shaggy because he's dumb to kind animals!
Video Wills: The phonograph record in "A Night of Fright Is No Delight".
The Walls Are Closing In: In "A Night of Fright Is No Delight", the gang discovered a locked trap door and a nearby organ that appears to control it. Scooby offers to play the organ to see whether they can open the trap door, but when that happens, the gang realizes the walls are closing in on them. As the gang tries to hold the walls back, Scooby desperately plays the instrument more, and then frantically dances on the keys to try to get it to stop the walls, and succeeds by sheer luck.
The message on the sheet music read, "Feed the organ and watch the floor," and Velma deduced that it meant the musical notes F-E-E-D, which she plays and a panel in the floor opens. As to which keys Scooby pushed to stop the walls, that is anybody's guess.
Scooby Doo: Music Of The Vampire: Shaggy and Scooby are told by swamp hermit Tulie that his prototype for hovering shoes was stolen by the vampire. When the gang catches the vampire, this is never brought back up. Likewise, we never see Jasper Poubelle and his vampire-hunting posse at the conclusion.
What the Hell, Townspeople?: In "To Switch a Witch", we see a group of 20th century townspeople behaving like a 17th century mob when they seek to torture an innocent girl to make her confess that she is a "witch". They even assault Shaggy and Scooby and subject them to the torture they'd intended for the girl. This includes the town's mayor. None of them are ever called on this or made to answer for it.
Who Is Driving?: Zig-zagged twice in the episode "Foul Play In Funland." First, Velma and Scooby are in a runaway bumper car which Velma can't control after losing her glasses (and she even taps her foot on the floorboard searching for a brake, which bumper cars don't have). Then, the gang is helping Mr. Jenkins find his recalcitrant robot in a jeep, which Velma's driving. And after the ride in the bumper car, where is Scooby sitting in the jeep Velma is driving? Shotgun!
Velma does show some mad skills with the Mystery Machine in Scooby Doo: Music Of The Vampire.
Daphne:(having just overpowered Zarkos) Now who's the damsel in distress?
Daphne: Straight up!
Who Would Want to Watch Us?: In Scooby-Doo and the Cyber Chase, the newly redrawn cast mock their original appearances in a video game based on them. (Cyber!Shaggy, however, is wearing his red shirt from a couple of the movies.)
Why, Thank You, X!: This happens a lot in Scooby-Doo, especially when Scooby and Shaggy decide to cook or just fool around after splitting up. The monster/ghost makes an appearance handing them something or offering a suggestion before they see it and run for their lives.
It also happened to Velma when she was in a college lab testing a mummy's bandages to find out if they were really ancient and the mummy handed her a test tube with the right chemical in it. (In retrospect, it's also kind of a clue that the mummy is one of the professors.)
Wild Wilderness: Well there are several locations from swamps to forests to islands to...well you get the point. They have to many adventures to really point this out to often but this trope swings in and out often.
Would You Do It For A Scooby Snack?: Normally with Shaggy and Scooby, but when Velma is offered a Scooby Snack in "A Terrifying Round With A Menacing Metallic Clown" to act as bait to catch the monster clown with Scooby, she refuses saying "I may be scared, but I'm not desperate." But she changes her mind when Daphne offers her a CD-ROM of the Encyclopedia ("King Tut, you're back in my life again!").
Writing Indentation Clue: One episode has Fred, Velma and Daphne come across someone's diary whilst looking for clues. They find that the ink of the text has faded, but the pressure of the pen has worn through to the next page. So one of them grabs a coal and shades the paper to see what was written.
Artistic License - History & Artistic License – Religion: Witch's Ghost treats witches and Wicca as two separate Witch Species, meaning a) one character claims his ancestor was a Wiccan who was burned at the stake 300 years before the religion was founded (granted, said character was lying and she really was a witch), and b) one of the Hex Girls is "one-sixteenth Wiccan".
Not to mention that there were never any witches burnt at the stake in America. They were either hanged, crushed with stones, or sentenced to imprisonment.
Younger Than They Look: They look like teenagers to you? Possibly lampshaded in the Valentine's Day special of What's New, Scooby Doo? where a flashback shows a much more teenage-looking Shaggy breaking up with his then-girlfriend. (It's a little subjective, but the beginning of Zombie Island heavily implies the characters are now college-age and subsequent animated versions of the franchise usually seem to tacitly follow suit even if the continuity is often vague...)