Human Names in Star Trek
Population nine billion - all British? Not only is human personnel prevalent in Starfleet, and not only are most of those humans definitely or supposedly Americans. It also seems that the overwhelming majority of supporting characters and extras are of English, Scottish or Irish origin, as indicated by their last names. The same applies to the first names as far as they are known. The situation is worsening with Enterprise where there seem to exist no humans outside the USA at all.
The following list classifies the human last names mentioned in Star Trek (main source: Encyclopedia III), not including those of holographic and other fictional characters and of individuals from a time before 2100 when nation states still existed. I may have missed several names and made some errors in linking them to countries (you need not mail me about everything), but it shows how predominant the writers have rendered the British/Irish heritage. No present-day American phone book has such a low share of non-British/Irish names, even if we take into consideration that immigrants often adapted by changing their names like from "Schmidt" to "Smith".
British/Irish (including now typical English names of Norman and Norwegian origin)
Adams, April, Archer, Arkinson, Ashmore, Bailey, Ballard, Barclay, Barnaby, Barron, Barrows, Barstow, Bartlett, Barton, Bates, Bateson, Baxter, Bennet, Bennett, Benton, Bernard, Biddle, Bilby, Blackwell, Blain, Bogrow, Boone, Boothby, Boyce, Boylan, Boylen, Brackett, Briggs, Bristow, Brooks, Brower, Brown, Bullock, Burke, Byrd, Cabot, Calloway, Carey, Carrington, Carson, Carstairs, Cartwright, Casey, Channing, Chapel, Chapman, Cheney, Childress, Chilton, Christopher, Clancy, Clark, Clendenning, Cogley, Coleman, Colt, Collins, Conor, Corbin, Corrigan, Crater, Crusher, Culhane, Curtis, Dalby, Darnell, Darson, Darvin, Darwin, Davies, Davis, Dean, Decker, Delaney, Dickerson, Douglas, Doyle, Duffy, Eddington, Edwell, Evans, Evansville, Farrell, Felton, Finnegan, Finney, Fisher, Fitzpatrick, Fletcher, Forrest, Fox, Franklin, Freeman, Fullerton, Garrett, Garrovick, Garth, Gentry, Gibson, Giddings, Gill, Gillespie, Gladstone, Gleason, Gordon, Gossett, Grady, Graham, Granger, Graves, Grayson, Green, Haines, Hanson, Hargrove, Harper, Harriman, Harris, Harrison, Haskins, Hawk, Hawkins, Hayes, Hayne, Hedford, Hendrick, Hengist, Henley, Henry, Henshaw, Hickman, Hill, Hobson, Hogan, Howard, Hubble, Hudson, Hutchinson, Jackson, Jameson, Janeway, Jarvis, Jellico, Jenkins, Johnson, Jones, Keel, Keeler, Keene, Kelly, Kelsey, Kennelly, Keogh, Kingsley, Kirby, Kirk, Kirkby, Kyle, Larson, Lawton, Leighton, Leonard, Lester, Lewis, Leyton, Locklin, Logan, Lyman, Lynch, MacAlister, MacAllister, MacDougal, MacDuff, Macormak, Maddox, Mallory, Markson, Marple, Marvick, Masters, Matthews, Maxwell, Mayweather, McCauley, McClukridge, McConnell, McCoullough, McCoy, McDowell, McFarland, McGarry, McGivers, McHuron, McKenzie, McKinney, McKnight, McLaren, McMinn, McWatt, Mears, Merrick, Miller, Minnerly, Mitchell, Molson, Moore, Morrow, Mudd, Mulhall, Murphy, Neeley, Neil, Nelson, Norris, O'Brien, O'Connell, ODonnell, ONeil, O'Neill, Palmer, Parsons, Pauley, Peeples, Pendleton, Piper, Porter, Potts, Powell, Quinn, Quint, Ramsey, Rawlens, Rayburn, Raymond, Reed, Reel, Reese, Remmick, Reynolds, Rhodes, Rice, Riker, Riley, Robertson, Robinson, Rogers, Rollins, Rollman, Rooney, Ross, Russell, Ryan, Ryson, Sanders, Scott, Seaborn, Shepard, Shaw, Shea, Shelby, Smith, Starnes, Stevens, Stiles, Stocker, Stone, Strickler, Stubbs, Sturgeon, Styles, Sullivan, Sutter, Swift, Swinn, Swofford, Taggert, Terrell, Thompson, Thorne, Tomlinson, Tracey, Travers, Tucker, Tyler, Underhill, Varley, Walker, Wallace, Warren, Washburn, Watkins, Watley, Watters, Wesley, Whatley, Wildman, Wilkins, Williams, Wilson, Willoughby, Wright, Wrightwell, Yates, Young
Rest of the world (Spanish, Italian, Scandinavian, German, Jewish, Polish, Russian and very few "exotic" names)
Anderson, Anthwara, Aquino, Arriaga, Atoa, Ayala, Baris, Bashir, Bendera, Berlin, Bertram, Beaumont, Bilecki, Boma, Brahms, Brevelle, Brianon, Bronovski, Chakotay, Chang, Chekote, Chekov, Colti, Cusak, D'Sora, Davila, Dehner, DeSalle, DeSeve, DeSoto, Diego, Dumont, Eiger, Esteban, Giger, Giotto, Girani, Giusti, Hagen, Hansen, Hastur, Helewa, Hendorff, Hildebrandt, Jaeger, Juarez, Kalomi, Karidian, Kenicki, Kelowitz, Kim, Kopf, Kosinski, Krajensky, Kyoto, Kwan, Lakanta, La Forge, Linke, Lin, Lindstrom, Loews, Lopez, Louvois, M'Benga, Malencon, Mandel, Mandl, Manheim, Mannus, Marquez, Masada, Mendez, Meyer, Molina, Moreau, Mulchaey, Muniz, Nakamura, Narsu, Ngomo, Nicoletti, Noel, Nogura, Novakovich, Nozawa, Ogawa, Palamas, Paris, Pavlick, Pechetti, Picard, Pulaski, Quintana, Quinteros, Ramirez, Rhada, Rodriguez, Romaine, Rozhenko, Sanchez, Santos, Sato, Schmitter, Seyetik, Singha, Sisko, Spinelli, Sulu, Tsu, Tannenbaum, Tessoni, Thule, Torres, Trumari, Tsingtao, U'Lanai, Uhura, Van Doren, Van Mayter, Van Gelder, Vanderberg, Vassbinder, Vigo, Wagner, Weiss, Wong, Woo, Yar, Yosa, Ziegler
Uncertain or multiple possibilities
Aaron, Albert, Arton, Aster, Barnhart, Bartel, Baytart, Beck, Benbeck, Bensen, Benteen, Brack, Branch, Brand, Brink, Brossmer, Cavit, Cobum, Corbin, Cory, Daren, Daystrom, Dern, Drazman, Dulmer, Durst, Emmanuel, Farris, Ferris, Flint, Galen, Gilhouly, Haden, Haftel, Hagler, Herbert, Holt, Horne, Jonas, Joseph, Kaplan, Kayden, Kelso, Korby, Lasca, Lang, Latimer, Lavelle, Lazarus, Lefler, Leijten, Lemli, Lense, Lessing, Lucier, Lucsly, Marr, Martin, Martine, Mendrossen, Menegay, Mullen, Mowray, Nara, Niles, Phillips, Pierce, Piersall, Pierse, Ramart, Ranar, Rand, Rifkin, Sandoval, Satie, Sharr, Sophen, Supera, Taitt, Telfer, Tormolen, Valtane, Wade, Zielen, Zweller
There may be different reasons why some 60% of all names are British or Irish. To a North American audience (and most of the rest of the world too) a name with the pattern "McSomething" sounds more concise and overall a lot cooler than "Papadopoulos", for instance. Also, thanks to Hollywood's obstinate adherence to the Nazi stereotype everyone expects that a good guy has to be named "Smith" and not "Schmidt". But this is still no apology for the Anglification of the world, for the silly habit of most authors who apparently pick their characters' names from a book of British/Irish genealogy, entirely ignoring the true composition of the world population in general and even of (white) American citizens in particular. Together with the observation that American places, customs and food are all-dominant in the fictional future, this definitely casts a bad light on Star Trek's intention to show how humanity may live in peace and explore space together.
Cultural Inconsistencies - inconsistent names, customs etc.
Thanks to Gregory Price for adding several names to the list.