->'''Newscaster:''' ...Turanga Leela.\\
'''Fry:''' ''Turanga?!''\\
'''Amy:''' That's her name, Philip.\\
'''Bender:''' ''Philip?!''
-->--''WesternAnimation/{{Futurama}}'', "The Problem With Popplers''

In many shows, the characters refer to each other by their [[FirstNameBasis given names]], and the audience refers to these characters as such. We refer to the friends of ''Series/{{Friends}}'' as Rachel, Phoebe, Joey, etc. This is usually the case in {{Dom Com}}s and other shows where many of the characters are related and therefore have the same last name. However, ''Series/TheXFiles'' could probably be considered the TropeCodifier, as that series took this trope to an extreme. Try thinking of a single character in that series who isn't referred to with either a descriptive title, or their last name.

In other shows, usually based on a shared workplace, characters refer to each other by surnames only. Nobody ever calls Series/{{House}} by his given name, Greg; not even his best friend, whom House also calls by surname, Wilson. Most of the characters on ''Series/{{CSI}}'' call Gil Grissom by his surname (as they do Brass, Hodges, and Ecklie). Accordingly, since this is the way the character is canonically addressed, fans will refer to them by their surname as well, sometimes to the point of forgetting a character's given name entirely.

(These characters are not [[TheyCallMeMisterTibbs referred to with titles]], either. It's not "Dr. House" to the other regulars. It's just "House.")

At times the LastNameBasis becomes jarring. When ''Series/{{House}}'''s Wilson began dating Amber (the only first-namer on the show,) she still referred to him as Wilson, possibly because the writers were so used to the name they just didn't think about it, and possibly because they thought the viewers might not know who "James" was. (This kind of situation may be used to set up a joke if the character has an {{embarrassing first name}}.)

Shows which use this trope can instill an artificial dislike for a new or guest character in the audience by putting them on a first name basis with the regular cast. They seem out of place as a result, which causes viewers to regard them as "bad" despite there being absolutely nothing to fault them for.

Sometimes there's a DoubleStandard for this trope: the same show may refer to men by their last names and women by their first names.

Initial use of this helps give FirstNameBasis significance; if the work begins with them on a FirstNameBasis, they can't switch in order to mark a significant increase in friendship or knowledge.

If only some characters in a work get this trope, it is frequently because they have a boring or common first name (like John), or an [[EmbarrassingFirstName embarrassing]] or [[WhoNamesTheirKidDude unusual one]].

LastNameBasis is TruthInTelevision for many non-US cultures; in Latin America it's not uncommon to see close friends calling each other by their last names, and using the family name plus or minus honorific is standard for Japan, where FirstNameBasis is a much more significant social statement.

Also TruthInTelevision for shows set in historical times (before about 1945 in North America and 1980 in the UK). In RegencyEngland, for instance, first names were only used by adults when addressing children (and parents when addressing their own children, even if they were adults), and among siblings or very close female friends. Husbands and wives only addressed each other by their first names when alone: in public or even amongst their family, they often referred to each other more formally. In many ways, the use of the first name became the English-language version of the French ''tutoyer'', as if addressing someone by their first name without a good reason showed that you didn't see them as your equal. While modern Americans see using the first name as friendly and egalitarian, someone from this time frame would see it as pushy, rude, and intrusive.

How much TruthInTelevision this is for modern US culture varies, especially for professional settings. Title-and-last-name-basis is often used in formal business relationships, for example with a customer or a boss. Even in less formal settings, LastNameBasis is seen among groups of coworkers and male persons, especially when there is a lot of first-name overlap. Female persons tend to stay with first names and tend to only use both first and last names if there is an overlap. It's also the standard in the US military, where you might be a bit hazy on the first name of your best buds.

Compare FullNameBasis, TheyCallMeMisterTibbs. Contrast HeyYou and TermsOfEndangerment.
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!!Examples:

[[index]]
* LastNameBasis/AnimeAndManga
* LastNameBasis/ComicBooks
* LastNameBasis/FanFic
* LastNameBasis/{{Film}}
* LastNameBasis/{{Literature}}
* LastNameBasis/LiveActionTV
* LastNameBasis/{{Music}}
* LastNameBasis/NewspaperComics
* LastNameBasis/ProfessionalWrestling
* LastNameBasis/{{Theatre}}
* LastNameBasis/VideoGames
* LastNameBasis/{{Webcomics}}
* LastNameBasis/WebOriginal
* LastNameBasis/WesternAnimation
* LastNameBasis/RealLife
[[/index]]


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[[folder: Roleplay]]
* In ''Roleplay/ThisIsWar'' Logan specifically tells Tex to refer to him by his surname.
[[/folder]]

[[folder: Web Animation]]
* In ''WebAnimation/{{RWBY}}'', Lie Ren is referred to in show as just Ren. This has been the subject of heated speculation about the customs of names in RWBY given that names of Asian origin in real life give the surname ''first''. However, Yang Xiao Long is referred to as Yang and we've recently learned her father's name is Taiyang, thus she is not referred to by her family name. Further, Ren lends the R to his team's name (JNPR), which parallels CRDL in that Sky Lark also seems to lend his surname. However, this is left unclear at this time as we have yet to hear anyone refer to Sky Lark by anything other than his full name.
** Roman is occasionally referred to as just "Torchwick."
[[/folder]]