Tweetie Pie: First time Sylvester and Tweety appear in the same cartoon.
Crowing Pains: Only cartoon to co-star Sylvester and Foghorn Leghorn
Catch as Cats Can
Back Alley Op-Roar: First cartoon to co-star Sylvester and Elmer. Semi-remake of an earlier short "Notes To You".
I Taw a Putty Tat
Hop, Look and Listen: First cartoon to have Sylvester and Hippety Hopper co-star.
Kit for Cat: With Elmer.
Scaredy Cat: First of three cartoons with Porky and Sylvester visiting strange places (the others are Claws for Alarm and Jumpin' Jupiter).
Bad Ol' Putty Tat: Starring Tweety
Hippety Hopper: Starring Tweety
Home Tweet Home: Starring Tweety
The Scarlet Pumpernickel: With Porky and Daffy.
All a Bir-r-r-rd: Starring Tweety.
Canary Row: With Tweety.
Stooge for a Mouse
Pop 'Im Pop!: Starring Hippety. First appearance of Sylvester Jr.
Putty Tat Trouble: Starring Tweety.
Room and Bird: Starring Tweety.
Tweety's S.O.S.: Starring Tweety
Tweet Tweet Tweety: Starring Tweety.
Who's Kitten Who?
Gift Wrapped: With Tweety.
Little Red Rodent Hood
Ain't She Tweet
Hoppy Go Lucky
A Bird in a Guilty Cage
Tree for Two
A Mouse Divided: First appearance of Friz Freleng's drunken stork character (there was a drunk stork character in Bob Clampett's Baby Bottleneck, but he was a One-Scene Wonder that may or may not have inspired Freleng's version of the character)
Tom Tom Tomcat: Hardly seen on American television due to the Native American stereotyping
Who Framed Roger Rabbit: Tweety in his original design appears in the Toontown skyline (nesting on a flagpole), and inexplicably reverts back to his original design and appears along with Sylvester in the ending.
Art Evolution: Tweety originally was a pink, featherless baby bird, but the Hays Office insisted that he don a yellow feather coat, due to objections of Tweety being "naked"—and yet they had no problems with Porky Pig not wearing pants!
In his initial appearences Sylvester was intended to resemble a baggy-pants comedian with a round belly, a low sagging pair of hips and an overly large red nose. This was toned down later, as the early design was hard to animate.
Played with personality wise. Sylvester's character was pretty much fully developed in his first appearance in "Life With Feathers" however as other directors took shots at the character he went through several different directions before returning to his original characterisation. Bob Clampett portrayed him as an extroverted Screwy Squirrel in "Kitty Kornered", while Art Davis used a dopier, more deadpan variant.
Ascended To Carnivorism: One short in which Sylvester and Tweety are Snowed-In features a mouse who hasn't eaten in so long he "forgot what food looks like." He takes one look at Sylvester and decides to have him for dinner.
Breakout Character: Both Granny and the bulldog character (later coined as Hector) made occasional appearances in initial shorts, and gradually became as much mainstream as the main duo. They are near equally prominant in Sylvester And Tweety Mysteries.
Demoted to Extra: Tweety became less active in later shorts, the main bulk of which revolved more around a bodyguard or alternate adversary guarding him from Sylvester (usually Granny or Hector).
Died Happily Ever After: Sylvester, who gets the last laugh on his foes in the afterlife in "Back Alley Oproar" and "Mouse Mazurka".
Early-Installment Weirdness: Tweety in his earliest appearances was a sadistic trickster who actively fought back against his aggressors. Once Freleng took over direction of the character, Tweety became a genuinely innocent, very passive character.
Flanderization: Tweety started out as a character that was cute but violent and hilarious at the same time in Bob Clampett Tweety cartoons. By the time Friz Freleng took over, Tweety was flanderized into a character that played cute only for the sake of being cute. On top of that, he was painfully unfunny.
Hidden Depths: Despite Tweety becoming softer, fans still speculate that he's still a sadistic being on the inside who takes pleasure in seeing Sylvester get hurt.
Invincible Hero: Tweety. Though he had a slightly more vulnerable streak than most other Looney Tunes protagonists, he was one of very few to come out the victor in every appearance he made.
Light-Flicker Teleportation: "Greedy For Tweety" did this: Sylvester is in a hospital bed and can't move, having been given sleeping pills. Every time he opens and closes his eyes, the dog appears closer and closer, wielding a club. It's prime Nightmare Fuel.
Motive Decay: Later cartoons put more spotlight on a protective bulldog (later named Hector in Sylvester And Tweety Mysteries) who guarded over Tweety. As such more emphasis was put on Sylvester trying to dispose of the dog to reach Tweety. Some cases evolve more into a vengeful Escalating War for his constant pummellings that he seems to forget about going after Tweety (eg. "Greedy For Tweety").
Not What It Looks Like: To avoid being blamed when another cat captures Tweety, Sylvester spent most of the episode trying to rescue Tweety from the other cat. In the end, while Sylvester was placing Tweety back in the cage, Granny reappeared and wrongly concluded Sylvester was capturing Tweety again. Quickly accepting she'd never believe the events prior, he prepares for his trip to the violin factory.
Pet Heir: Sylvester is left a fortune (and all of its attendant problems) in "Heir-Conditioned".
Ping Pong Na´vetÚ: Just how innocent Tweety is in his dealings with Sylvester is part of the gag. Granny's awareness of Sylvester antagonizing Tweety also varies from short to short.
Samus Is a Girl: Given Tweety's falsetto voice, many are the people who still don't know he's a boy. Despite that he's been seen swooning over women.
It doesn't help in almost every foreign-language dubbed version, Tweety is voiced by women who sometimes don't bother to make him sound remotely male.
Team Rocket Wins: Sylvester never won against Tweety, though got the last laugh in a handful of alternate appearances. He succeeded in eating an Asshole Victim parrot in "Catch As Cats Can" and outwitted Porky in throwing him out for the night in "Kitty Cornered".
Threatening Shark: Towards Sylvester, that is, in the latter-day short "Hawaiian Aye Aye", who tries all he can to keep Tweety safe.