Brigandia: A guild known for looting and PKing unsuspecting players. It was led by Demikas until its disbandment at the hands of Silver Sword.
Akiba
Round Table Council
- Log Horizon: It was founded by Shiroe who, prior to the Catastrophe, had avoided joining any guilds despite numerous invitations and offers. After discovering that both Tohya and Minori, along with 33 other beginners, were being enslaved by the Hamelin, he decided that the best way to help Tohya and Minori as well as his friends Naotsugu, Akatsuki, and Nyanta in the post-catastrophe world was to form his own guild. With a small push from Nyanta, he founded Log Horizon with his former party members and new friends as co-founders.
- D.D.D.: A powerful guild in Elder Tale. It is the largest battle guild in Akihabara and has more than 1,500 members, including many who are level 90. It's led by the "Berserker" Krusty.
- Black Sword Knights: A guild founded by Black Sword Isaac. Known for being elitist and considered as a pure-blooded battle guild, it has the policy of only accepting members that are on level 85 or higher. Due to this policy that they upheld even after the Apocalypse, potential members are limited, making it possible for rival guilds like D.D.D to overtake them in numbers and strength.
- Honesty: Although Honesty is a battle guild, it is far less competitive than guilds like D.D.D and the Black Sword Knights. The guild focuses on clearing dungeons and creating guides for other players, and has a policy of sharing information. That policy puts it into conflict from time-to-time with the other battle guilds.
- Silver Sword: A guild in Elder Tale. It's one of the most influential guilds in Akihabara and one of the four major battle guilds. Silver Sword was originally supposed to be a member of the Round Table Alliance but its Guild Master, William Massachusetts, refused to join. After the Alliance proves to be a success, he and the rest of Silver Sword leave for Susukino.
- West Wind Brigade: A guild located in Akihabara boasting to have 120 members but, in reality, with more or less sixty. Infamously known as a harem guild, it was founded by Soujiro Seta, a former member of the Debauchery Tea Party. Currently, it is one of the most influential guilds in Akihabara, standing in equal ground with big guilds such as D.D.D, Black Sword Knights, Silver Sword, and Honesty.
- Marine Organization: A production guild in Elder Tale. They are one the largest and most powerful trade guilds in Akiba. Their guild is one the 11 founding members of the Round Table Alliance. It has the highest stated number of members in the new world. Notably it is also one of the three guilds that funded Shiroes purchase of the Guild building.
- Shopping District 8: Started as a chatting guild then transformed into a production guild, Shopping District 8 is the third largest production guild in Akiba. It's named after the hour 8 PM, which was the most prosperous time to do business, before the Catastrophe, when Elder Tale was still just a game.
- The Roderick Firm: The second-largest production guild in Akiba. After the Apocalypse, this guild focused on research and attempted to gather every kind of recipe and item.
- Grandeur: Founded by Woodstock W after he left the Black Sword Knights due to its elitist policy. With this background, Grandeur was founded to be open to all players and was known before the Catastrophe for hosting parties in the real world outside of the game to welcome new members.
- Radio Market: A small, Akiba-based production guild in Elder Tale. It is lead by Guild Master Ichimonjinosuke Akaneya.
- Crescent Moon Alliance: At the start of the series, the Crescent Moon Alliance is a small guild with fewer than 30 members (only 19 were online at the time of the Catastrophe). The level of the guild's members is also low—only four players are level 90, and over half of the remaining members are below level 50. The guild's membership has grown to 65 members. Despite its small size, the guild is a member of the Round Table Alliance. Crescent Moon Alliance is seen to be a guild for training low-level players and a sister guild of Log Horizon due to frequency of interactions.
- Amenoma: A weapons production guild operating in Akihabara. It specializes in the production of Japanese swords and is well known among the city's residents. Mostly consisting of high-level Blacksmiths, the guild members are dedicated in their trade and are said to have near-freakish obsessions with quality.
- Blue Impact: One of the PK guilds that gained notoriety around Akihabara after the Apocalypse. They ambush and PK players around Akihabara in order to loot the items and gold they drop after their deaths.
- Canossa: One of the PK guilds that gained notoriety around Akihabara after the Catastrophe. They ambushed players around Akihabara in order to loot the items and gold they drop after their deaths.
- Cocoa Brown: A small guild operating in Akihabara. Not much is known about the guild but some of its members specialize in the production of small accessories ranging from precious stones of various colors to delicately crafted necklace and earrings that they sold during the clothing expo of the Libra Festival. Their products were considered very classy but the guild members decided to sell them at low prices and sparingly as a way of showing their gratitude for the support given to them by large guilds.
- Dread Pack: One of the PK guilds that gained notoriety around Akihabara after the Catastrophe. The guild mostly consists of six members with high levels: a samurai, two swashbucklers, a druid, a sorcerer and a summoner. They ambush players around Akihabara in order to loot the items and gold they drop after their death.
- Hamelin: A medium-sized guild in Akiba. Disguising themselves as helpers for newbies and recruited many of them during the Catastrophe. Revealed to be, nothing of short, slaver of the newbies, working them to the bone & taking their EXP Pots, selling it to Battle Guilds like Black Sword Knights. They were eventually (forcefully) disbanded by Shiroe after locking them out from the Guild Hall, forcing them to fend for themselves.
- Tidal Clan: One of the PK guilds that gained notoriety around Akihabara after the Catastrophe. They ambush players around Akihabara in order to loot the items and gold they drop after their death.
Minami
Plant Hwyaden: The guild holds complete control of Minami and Nakasu, the latter of which was actually suppressed under the guise of a merging with Plant Hwyaden.
Although Plant Hwyaden is the official guild of both cities, within the guild there are several subdivisions, such as the Wolves of Mibu. The guild is also headed by the Ten Seat Conference, individuals either hand-picked by Indicus or added by the Lander nobles to have representation in the city's affairs.
Nakasu
Light Indigo: Little is known about Light Indigo, and Vuorinen calls it an "unknown guild.". Tetora calls it a "holding place," and, after being questioned by Naotsugu, continues on to say that they "exist to protect the homes in everyone's heart." She also mentions, perhaps in reference to Plant Hwyaden and the situation in Minami, that the members of the guild are unsure of what to do.
Chinese Server
Lelang Wolf Cavalry: Not much is known about this guild, but it was one of the most famous guilds on the Chinese server. It is well-known in the Yamato server for the members' unique playing style, which consisted of riding a wolf mount unique to China.
Oceania Server
Green & Green: A massive international pacifist guild based in Perth, Australia. They seem to serve the same role as the Round Table Alliance and Plant Hwyaden, acknowledging that Landers have rights, kicking out PKs or anyone that harasses Landers, and becoming the Australian landmass' sole guild. Green & Green is also clearing out monsters so they can work towards finding a way home.