Nick provides a long list of party attenders at one point, including:

the Fishguards, the Snells, the Dancies, S. B. Whitebait, Maurice Flink, the Hammerheads ... the Poles, the Mulreadys, Cecil Roebuck, Cicil Schoen, Gulick, Newton Orchid, Eckhaust, Clyde Choen, Don Schwartze, Arthur McCarty, the Catlips, the Bembergs, Muldoon, Da Fontano, Ed Legros ...

While most of the names do not sound at all prestigious, we do know that some important people occasionally come, including a film producer and a state senator. Names of the people who attend the parties who actually play a role in the novel include the Owl-eyed man and Klipspringer, as well Jordan Baker.

Two points can be made about the guests. First, Gatsby opens his door to everyone indiscriminately and so pulls in a vast array of guests from all walks of life. The parties can be seen as a manifestation of American democracy, a melting pot of all sorts of people. This diversity helps give the parties their energy. Second, however, the parties do not attract many people from Tom and Daisy's wealthy and upperclass set. Jordan comes, but Tom and Daisy never do until Gatsby manages to reunite with Daisy.

The guest list and the party Daisy attends leaves her unhappy and uncomfortable, something Gatsby notes. This speaks to an underlying disconnect between Gatsby and Daisy, and it suggests that Daisy wants to stay cocooned in her separate world. Gatsby ends the parties after he finds Daisy doesn't like them, but that doesn't close the gap between the two of them.

At the beginning of chapter four, Nick recites a lengthy list of people who attended Gatsby's parties over the summer. To some, he attaches their professions, claims to fame or notoriety, or from where they come.

From East Egg, Nick lists many couples, a doctor, a classmate from Yale, a couple in which the wife is stepping out on her husband, and some unattached men. There were also people from "farther out on the island," which could mean the Hamptons; among them are society types and those notorious for crimes.

From West Egg came people who are less wealthy or perhaps newly wealthy; among them are a "state senator," the owner of a film company, various people connected with film-making, a promoter, and corporate titans who came to gamble.

There were people from the theater world of New York City, various hangers-on, and a foreign prince. There were musicians, caterers, a movie star and her producer, and a group of young Brits hoping to make business connections.

All of the principal characters of the novel attend at least one of Gatsby's parties, with the exception of George and Myrtle Wilson. Catherine, Myrtle's sister, says she has been to Gatsby's. And of course, Nick and Jordan attend more than once and Tom and Daisy, just once.

And the man whom Nick calls "Owl Eyes" attends not only Gatsby's parties, but his funeral, as well.

At the first party Nick attends, there is a "stout, middle-aged man, with enormous owl-eyed spectacles" who is drunk and hanging out in the library at Gatsby's house. When Nick and Jordan walk in, he is closely examining the books on the shelves, and he is shocked and pleased to report that the books are real. Apparently, he'd expected them to be made of cardboard, but they are real books with pages and everything. He produces one book, as if to prove it, and he cries out,

"See! . . . It's a bona-fide piece of printed matter. It fooled me. This fella's a regular Belasco."

David Belasco was a theater impresario, producer, director, and playwright. He was, apparently, very creative and came up with new forms of lighting and special effects which would help to produce a greater sense of realism on his sets. Therefore, when the owl-eyed man calls Gatsby a regular Belasco, he is implying that Gatsby has staged his whole house the way Belasco might prepare a set for the theater. Further, he says, 

"Knew when to stop, too—didn't cut the pages."

Although the books are real, then, they must not ever have been read because the pages are uncut. The owl-eyed man seems impressed by Gatsby's restraint: he bought real books, but he didn't cut the pages and try to make it look like he'd actually read them.

That is a vast list from both East Egg, West Egg, and beyond!  Let me begin with the most important in regards to the novel itself:  Daisy Buchanan, Tom Buchanan, Jordan Baker, and Nick Carraway.  However, as Nick relates at the beginning of Chapter 4:

Once I wrote down on the empty spaces of a timetable the names of those who came to Gatsby's house that summer. (61)

The list of names, then, is contained within that same chapter.  Those who came to Gatsby's parties from East Egg are as follows:  the Chester Beckers, the Leeches, Bunsen, Doctor Wbster Civet, the Hornbeams, the Willie Voltaires, the Blackbucks, the Ismays, the Chrysties, Edgar Beaver, Clarence Endive, the Cheadles, teh Schraeders, the Abrams, the Fishguards, the Snells, the Dancies, S. B. Whitebait, Maurice Flink, the Hammerheads as well as Beluga (and his girls).  Those who came to Gatsby's parties from West Egg are as follows:  the Poles, the Mulreadys, Cecil Roebuck, Cicil Schoen, Gulick, Newton Orchid, Eckhaust, Clyde Choen, Don Schwartze, Arthur McCarty, the Catlips, the Bembergs, Muldoon, Da Fontano, Ed Legros, James Ferre3t, the De Jongs, Earnest Lilly, Klipspringer, Gus Waize, Horace O'Donavan, Lester Myer, George Duckweed, and Francis Bull.  There was also a clan that came from New York and elsewhere:  the Chromes, the Backhyssons, the Dennickers, Russel Betty, the Corrigans, the Kellehers, the Dewars, the Scullys, Belcher, the Smirkes, the Quinns, Henry Palmetto, Benny McClenahan (and his girls), Faustina O'Brien, Ms. Baedeker, Brewer, Albrucksburger, Miss Haag, Ardita Fitz-Peters, Mr. Jewett, and Miss Claudia Hip.

Further details can be found about many of these people in the confines of Chapter 4.  For example, the people from East Egg (who are known to be "old money") are most often referred to by family while the people from West Egg (who are known to be "new money") are referred to by specific name.  No matter what, one can admit that Nick was quite observant!