The role of Julia Louis-Dreyfus in Seinfeld is, arguably, the most important female sitcom character ever created. Elaine Benes changed the very fabric of comedy by instituting herself within a heavily male-dominated artform; her massive success being the proof that women can be as funny (or as nasty) as any man.
Although she's absent in a couple of episodes, her presence can be felt throughout the rest, often eclipsing Kramer's slapstick, Jerry's ennui, and George's self-hatred with her own brand of antics. Here are a few examples in which Elaine shines at her brightest.
The Little Kicks (S8, E4)
George watches Elaine make a complete fool of herself by attempting to "dance" at an office party, as he later describes to Jerry as a "full-bodied dry heave set to music." She refuses to even consider such a possibility, claiming that her staff now makes fun of her because George's loser aura ruined the party for her.
Kramer and Jerry admit that her dancing "stinks", so she records herself in the act to make sure her friends aren't just messing with her. In the end, the gang (except Elaine) try to replicate her awful moves when her back is turned.
The Subway (S3, E13)
George skips a crucial interview to sleep with a random woman on the train, getting himself robbed naked. Jerry has a calm, yet fatphobic, discussion with a naked man in his subway car. But it is Elaine who makes the most of this episode, starting with her trying to explain how lesbian weddings work to another passenger and ending (?) with a horrifying scenario — getting stuck in a stalled subway, which is bad enough without the power having to go out as well, which it obviously does.
Elaine's ramblings almost make audiences feel sorry for her. Almost. Kramer is the only one to end this episode on a good note (though he almost gets himself mugged in the process.)
The Beard (S6, E16)
It's strange to watch Jerry being the voice of reason here, as he tries to convince Elaine that her dreams of "converting" a gay man will end in misery. She goes for it anyway, pretending that she only means to be a "beard" for one of her gay acquaintances, so he can avoid getting fired because of his identity.
In fact, it looks like she has actually succeeded, slyly implying that she hooked up with Robert and that he has "defected." Time, however, is not kind to Elaine: she discovers that he's "gone back" to "being gay" again, as Jerry sagely muses about his baseball metaphors for sexuality.
The Airport (S4, E12)
Jerry and Elaine are accidentally upgraded to first class on their flight back to NYC, but there's only one seat (which he grabs.) Elaine is forced to endure the horrors of coach while Jerry basks in the warmth of privilege, making this episode a vague parody about class systems and hierarchy.
She struggles with the passengers seated next to her, finally managing to make her way to the bathroom before her bladder bursts, but then has to wait until the flight attendant passes with his food cart before she can get back to her seat. If that's not enough, Elaine's luggage is intentionally "lost" because she antagonizes a baggage handler.
The Stand In (S5, E16)
Jerry sets Elaine up on a date with, Phil Totola, a pal of his, and the pair really seem to hit it off. At first. Right before dropping her off at the apartment, though, they have a hilarious moment in the car when she describes the "Pachyderm" story — a mysterious tale that remains to this day an unsolved joke about how "the whole place 'went crazy' when one piece landed on Pachyderm's face and the other landed on the woman's face."
Unfortunately, Phil takes the opportunity to expose himself to Elaine, or, as she says, "he took it out." Whether this was a commentary about sexual abuse is still unclear.
The Pen (S3, E3)
This is one of the earliest episodes in which Elaine's melodramatic character begins to show itself. On a visit to hot and humid Florida, she and Jerry bunk with his parents (where she fitfully sleeps on a demonically uncomfortable sofa-bed.)
In the morning, her back is so out of shape that she overdoses on Morty Seinfeld's muscle relaxants, which leaves her in a semi-conscious state of zero inhibition. Elaine's genius/disastrous rendition of Marlon Brando from A Streetcar Named Desire (1951) makes everything worthwhile, at least for the audience.
The Susie (S8, E15)
Elaine is constantly confused for an unknown woman called Susie by Peggy, an exhausting colleague. She plays along until Peggy starts talking trash about her (the real her), not knowing what she looks like for obvious reasons.
Elaine finds herself getting angrier and angrier, not so much because her co-worker considers her a worthless addition to J. Peterman but because she keeps calling her "Suze." By the conclusion, Elaine gets rid of her fictitious alter ego by claiming that Susie "took her own life," who then gets a fake funeral, much to the real version's annoyance.
The Tape (S3, E8)
Elaine playfully records an extremely sexual voice note on Jerry's tape recorder during his stand-up performance, but the boys soon become enamored with how shameless and welcoming her voice sounds. George is the first to find out, but he immediately discovers a burgeoning attraction towards her (based on his alternative perception of her.)
In the end, George and Jerry stand leering at Elaine, almost as if they're overlaying her face with the "sexy voice" they had heard; noticing this change in atmosphere, she quickly makes her exit while the others fight over getting listening rights to the tape.
The Reverse Peephole (S9, E12)
Elaine has a tendency to go on rants about animal rights or the environment — like when she begs Jerry not to order tuna because of "those poor dolphins" — but her activism is usually revealed to be spurious. In "The Reverse Peephole", she hates the idea of Puddy and his fur coat, so she accidentally gets rid of someone else's garment thinking that it is her boyfriend's.
Thankfully, he is turned off the idea after seeing Jerry wearing it (because "he looked a bit like a dandy"), so he opts for a polychromatic leather outfit that is as bad in Elaine's eyes as his previous choice, proving that she cares more about aesthetic than her so-called ethics.
The Soup Nazi (S7, E6)
It is a wonder how Kramer manages to make friends with everyone he meets, even those as antisocial as the Soup Nazi. On the contrary, Elaine's relationship with the grouchiest caterer in NYC is based on rage, arrogance, and a deep desire for vengeance.
After the Soup Nazi proclaims a one-year ban on her entry, she discovers most of his secret recipes hidden in his old armoire (that she buys without realizing it.) Armed with the perfect weapons, she trots down to the soup stand and basically destroys his vocation in the most extravagant manner imaginable.