Black Sheep: Extremely out-of-place in his Big Screwed-Up Family, he hardly gets along with any of his relatives. His Aunt Agatha disapproves of his lifestyle and spends a lot of time trying to turn him into a credit to the name of Wooster, to no avail.
"Now is the time for all good men to come to the aid of the party."
(in the narration) "… And I meant it to sting."
"… if that's the word I want." / "What's the word I want?" / "That's the word I want."
"The Code of the Woosters". (In the same vein, beginning sentences with "We Woosters..." or "We Woosters know when...")
"Thank you, Jeeves."
Child Hater: Justified due to the series' constant use of the Bratty Half-Pint trope. He does have a fondness for little girls, although even that tendency seems to have vanished as of "Bertie Changes His Mind".
Chick Magnet: Although he claims to have bad luck with women in general, even he's noticed that he has a remarkable tendency to attract exactly the kind of girl he most fears.
"I mean to say, I know perfectly well that I've got, roughly speaking, half the amount of brain a normal bloke ought to possess. And when a girl comes along who has about twice the regular allowance, she too often makes a bee line for me with the love light in her eyes. I don't know how to account for it, but it is so."
The Ditherer: Due to letting Jeeves run his life. Aunt Dahlia actually calls him "poor ditherer" in one story.
Drama Queen: Everything he does is Serious Business, to the point where retaliation in a prank war is a heroic defense of the Wooster name likened to participation in the Crusades. After being forced to sing at a "clean, bright entertainment", he goes into Shell-Shocked Veteran mode, insisting that the pain he went through was "unparalleled since the days of the early Martyrs."
Dreadful Musician: Not as a general rule—even if you don't count his excellent piano playing in the TV series, he's said to be a good singer with a "light, pleasant baritone". Though his playing of the banjolele in Thank You, Jeeves isn't terrible, his sheer devotion to it causes his neighbors in the flat collectively give him the ultimatum to give it up or clear out, and even Jeeves deserts him rather than put up with it in isolated quarters. (When the TV series adapted the plot, the banjolele was replaced with a trombone.)
The Dulcinea Effect: He suffers from this regularly at first, only to regret his impulsiveness. Bobbie Wickham, Gwladys, and (in backstory) Pauline Stoker are examples.
Embarrassing Middle Name: His middle name is Wilberforce (his father won money on a horse named Wilberforce a day before Bertie was born), which seems to cause him varying levels of discomfort depending on his mood. May count as a Genius Bonus joke; the name "Wilberforce" is best known as the surname of various famous evangelicals and social reformers, but instead Bertie got it through his father's gambling addiction.
Et Tu, Brute?: His reaction upon being betrayed or let down by Jeeves.
Expy: Of Wodehouse's earlier character Reggie Pepper. A few of Reggie's stories were even rewritten to star Bertie (with Jeeves in tow) instead.
Extreme Doormat: He can be talked into pretty much anything. He suffers the worst of one Zany Scheme after another because he's simply unable to say "no" to a friend or a girl. Besides that, he's afraid to stand up to his aunt, and he lets Jeeves dictate every facet of his existence, even down to the details of his wardrobe. Attempts to assert his rights by keeping an article of clothing Jeeves disapproves of invariably give out by the end of the story.
Genius Ditz: He thinks of himself as such, since when it comes to figuring out if people are in love, he is "Hawkshaw the Detective himself in person". In a slight meta-example, as many critics have pointed out, he has a gift for language and humorous phrasing, due to being written by P. G. Wodehouse. The TV series made him an accomplished piano player, as well.
Gentleman and a Scholar: Strangely enough, the "mentally negligible" Bertie fits this trope. He's definitely a gentleman, always well-dressed, believing in Sacred Hospitality and honourable to a fault, but if you look at his prose style you can see that he's half-forgotten more classic English literature than most of us managed to learn in the first place.
Gratuitous French: He often uses French phrases, sometimes wondering if they're correct.
Most fellows, no doubt, are all for having their valets confine their activities to creasing trousers and what not without trying to run the home; but it's different with Jeeves. Right from the first day he came to me, I have looked on him as a sort of guide, philosopher, and friend.
Obfuscating Insanity: More than one scheme has been pulled off only because Jeeves told everyone involved that Bertie was insane. This doesn't make him happy in The Inimitable Jeeves, but by Very Good, Jeeves! he's gotten used to it and even goes along with it if necessary.
Slowly increases over the course of the series - largely due to Jeeves. Honorable mention goes to the Reverend Aubrey Upjohn, Bertie's grammar school teacher, whose efforts to pump English literature and culture into Bertie's vacuous skull must have been truly Herculean.
The So-Called Coward: He cheerfully acknowledges his cowardice in the television series, along with his quite rational fear of the latest spurned fiance out for his blood, but nonetheless always ends up facing them.
Interestingly, despite his innate fearfulness, Bertie will almost always face any peril if it's a matter of chivalry, nobless oblige, a bet, or supporting a pal. Except where Aunt Agatha is involved.
Ascended Extra: Literally. In the first short story featuring Bertie, "Extricating Young Gussie", he simply appeared in the background as the necessary valet, and, according to Word of God, was never intended as anything more than that. It wasn't until the second story that he became the conniving genius of a gentleman's gentleman we know today.
Battle Butler: Generally handles things with his wits alone, but is equally able to descend to violence if the situation calls for it.
Blue and Orange Morality: Assisting his master in theft, blackmail and gambling is perfectly fine. Errors in dinner dress are not.
Cloudcuckoolander's Minder: Almost to the point of being The Caretaker. Aunt Agatha has referred to him as Bertie's "keeper", and he doesn't even go on vacation without making sure that Bertie is staying with friends, relatives or a substitute valet.
Living MacGuffin: Most of Bertie's friends want him to work for them, and at least one offered him twice the amount Bertie was paying him. When he gives notice in Thank You, Jeeves, he goes into what Bertie refers to as "circulation". Bertie's friend Chuffy snatches him up almost instantly, and he proceeds to quit Chuffy's service when American millionaire J. Washburn Stoker offers him a position. Then he goes back to Chuffy and finally returns to Bertie, who is less than eager to let him go again.
I had had no inkling of his approach, but then one very often hasn't. He has a way of suddenly materializing at one's side like one of those Indian blokes who shoot their astral bodies to and fro, going into thin air in Rangoon and re-assembling the parts in Calcutta. I think it's done with mirrors.
Verbal Tic: Perhaps not so much a verbal tic as a respectful habit, but still, he says "sir" in almost every sentence he speaks to Bertie. This made for a bit of comedy in the TV series when he and Bertie tried to sing a Call-and-Response Song.
Vitriolic Best Buds: He snarks at Bertie, manipulates him, gives him the cold shoulder when he most wants sympathy, gets him into trouble, and destroys his stuff. Why? Because he cares.
...my Aunt Agatha, who eats broken bottles and is widely rumored to turn into a werewolf on nights of the full moon.
The indomitable and haughty Mrs. Spenser-Gregson (later Lady Worplesdon). Her lightest word is to Bertie as the Trump of Doom.
She might be considered more of a Designated Villain: Although proud, domineering and impatient with fools, Agatha spends an unusually large amount of time trying to ensure that the honor of her original family name is not dragged through the mud by the dunderheaded antics of her nephew.
Family Honor: Her obsession. She's willing to go even as far as bribery to keep family members from marrying into common blood.
Pet the Dog: In the most literal sense. She has a friendly little terrier, Macintosh, to whom she is very attached.
Impoverished Patrician: Sort of. Her husband Tom is in fact immensely wealthy, but getting him to cough up even trivial amounts of money for her latest pet project is much like squeezing blood from a stone.
The Teetotaler: His drink of choice is orange juice. In one episode, after getting chased by Constable Oates, he asks for some brandy (as that is what people do when stressed, he says), and finds it to be disgusting.
Stinker saw me and immediately upset a side table, his invariable practice whenever he's anywhere that there's furniture.
Beware the Nice Ones: He's one of the most genuinely amiable and friendly characters in the series, and normally wouldn't hurt a fly — but he's an unstoppable rugby player, and if you threaten his loved ones he'll lay you flat with one punch.
The Prankster: Bertie admires her "espiglerie"—French for "impish or playful behavior". He's a bit less amused when she gives him an idea for a prank against Tuppy and then turns out to have fed Tuppy the same idea.
Bertie: "I agree that any red-blooded Sultan offered the chance to add Madeline Bassett to his harem would leap at the chance, but he would be regretting the gesture before the week was out. What he would be overlooking in undertaking this rash act is her squashy soupiness. She's the sort of girl who believes that the stars are God's daisy chain and every time a fairy blows its wee nose a baby is born, which as we know is not the case."
Abhorrent Admirer: To Bertie. Unlike most examples of the trope, she's not ugly - she's actually very attractive, but unbearably sentimental.
...to do this revolting duo [Madeline Bassett and Honoria Glossop] justice, neither had tried to mold me, and this was what Florence Craye had attempted to do from day one, seeming to regard Bertram as little more than a blank lump of plasticine in the hands of the sculptor.
Abhorrent Admirer: To Bertie again. She's very attractive - that's why he engaged her - but she has a horrifyingly caustic personality.
Minor Flaw, Major Breakup: Inverted. Despite the fact that she's mean, manipulative and utterly unsuited to Bertie in every way, besides being the kind of girl he typically avoids, he stays with her because she has a nice profile.
She, on the other hand, is wont to ditch fiancés who let her down in any way (if only by failing to be moulded fast enough)
Not So Different: Though at first he and Bertie couldn't appear more different it turns out that they both stole biscuts from their headmasters when they were kids and that Sir Roderick used to help his buddies with their hairbrained schemes.
Psycho Psychologist: Though a mild example of this trope, a lot of his ideas are extremely misguided not the mention the fact that he seems more neurotic than some of the people he believes to be mentally ill (i.e. Bertie)
Our views on each other were definite. His was that what England needed if it was to become a land fit for heroes to live in was fewer and better Woosters, while I had always felt that there was nothing wrong with England that a ton of bricks falling from a height on Spode's head wouldn't cure.
...about as 'safe' as a pair of sprightly young tarantulas.
Alcohol-Induced Idiocy: In their very first appearance, they're arrested for trying to pinch a motor-lorry while drunk.
Put on a Bus: In "The Delayed Exit of Claude and Eustace", they're sent to South Africa after being expelled from Oxford, and, although they resist at first, they end up going willingly thanks to Jeeves.
Uptown Girl: The premise of all her novels. In fact, part of the reason she falls for Bingo is that he goes after her while she's pretending to be a waitress, thereby proving that class differences don't matter to him.
...he is the fellow managers pick first when they have a Society comedy to present and want someone for 'Freddie', the lighthearted friend of the hero, carrying the second love interest. If at such a show you see a willowy figure come bounding on with a tennis racket, shouting 'Hallo, girls' shortly after the kick-off, don't bother to look at the programme. That'll be Catsmeat.
...smallish, plumpish, Gawd-help-us-ish... As to his manner, I couldn't get a better word for it at the moment than 'familiar', but I looked it up later in Jeeves's Dictionary of Synonyms and found that it had been unduly intimate, too free, forward, lacking in proper reserve, deficient in due respect, impudent, bold, and intrusive.
Accidental Misnaming: Apparently, as Jeeves informs Bertie in Much Obliged, Jeeves, his name isn't Brinkley, but Bingley. Seems Bertie called him by the wrong name for an entire book without discovering he was in error.