The Player

The Player (also known as "Pretender" by the Simulacra and "Voyeur" (As of the game page) is the unnamed protagonist of Simulacra and the driving force of the story, as they are the one with Anna's phone. Anna's phone was delivered to The Player's house, after which they picked it up and began to use it, browsing through Anna's content and talking to her friends in an effort to find her.

As The Player is never seen in-game, The Player is classifiable as a standard "Featureless Protagonist", meaning that they hold no identity or characterization except the bare minimum necessary for a character to be considered a character, as the player is supposed to fill the role of the protagonist. However, they serve as the entire driving force of the story, as they possess the exclusive means to find and track down Anna which leads to other characters relying on them very heavily.

After Anna's phone resets, The Player receives a chance to make themselves into a character by going through a questionnaire posed by the phone's IRIS software starting with inputting their name, ranging from technical questions, such as "Are you a new or experienced user?", to casual conversation "Where do you live?", all the way up to "Would you rather know the cause of your death or the date of your death?" before either being complimented on the smell of their hair or asking if they can have their hair touched by the Simulacra.

Although there are no indications for canon options in the questionnaire, the slide show displays what looks like The Player receiving the phone at the beginning, with it showing up on their doorstep, The Player going through it curiously, the Simulacra smelling/touching their hair, all the while shown in the stereotypical minimalist art style often showcased by technological companies. The Player has an ambiguous gender, but if you get to the part where you ask Taylor "Type?" when he tells you to set up a Spark profile, he assumes that the player has a type, leading to him questioning the Player's gender, where you may define your character as a male (which will disappoint Taylor, then get him back on track), a female (which will cause Taylor to develop a 1-second infatuation with the player, then get back on track), or non-binary (which Taylor will take some time to perceive and then show his support for the gender-queer community, then get back on track).

Personality
The Player is a standard Featureless Protagonist, meaning that they act as a blank slate that the real player is supposed to project onto, however, the protagonist's dialogue options do reveal a lot about themselves as a person, which is that they're essentially nobody, which they themselves attest to by telling someone else "I'm nobody, really" after being asked who they are. They do have a strong capacity to be confrontational and sassy at times, however, the dialogue options also allow for The Player to relegate themselves to nothing more than a passive waste. Canonically, it seems like they are a person of general competence with no defining features other than determination on account of their insistence on saving Anna and not much more, however, they have proven gifted in puzzle solving as that is their main way to interact with the story.

Compared to the Sara Is Missing protagonist who broke under pressure very easily and broke down into mindless cursing when overwhelmed (the situation was different because they were watching people die), the Simulacra protagonist makes an attempt to keep a level head under the most impossible circumstances and curses very selectively in casual conversation but surprisingly never curses under pressure, instead opting to be quickly tactical with their word choices by conveying information and orders.

Their self-acknowledgement that they're nobody could pose a philosophical dilemma about the self-realization of being nothing more than a person who anyone could be in that moment - a sort of commentary on how little characterized Featureless Protagonists are in direct opposition to how monumental their role is in pushing the story forward.

Simulacra: Pipe Dreams
The protagonist of Simulacra: Pipe Dreams goes by the handle "UserCruiser" and is likely a different person from the Simulacra protagonist.

Simulacra 2
In the second game you start off with an option screen deciding who you, the player, are. The option you pick upon is your first choice in the game, your opening decision seems to have some importance over the text responses the game gives you (so there's nice re-play ability). Of course it's still a semi self-insert character, So practically this gives us a self-insert, but with a bit of character. You have two options including:

Tabloid Reporter
The opening for the Tabloid reporter reads "You're a tabloid reporter, and frights are your beat" . When Detective Murilo and you first meet you were invited by him to help him with something (not specified in the first scene) He gives you the phone and walks away. From this short brief cutscene we learn a bit about out tabloid reporter, assuming from their title (Tabloid Reporter) and the line "...a newspaper hack like you" means they must write on some blog or newspaper that is well known for his like in "frights" (mentioned earlier) further proven when Murilo went on to say "I think this case is right up your alley". Murilo mentions that the Tabloid Reporter is the self-proclaimed best at digging up dirt "you say your the best at digging up dirt huh? Well this is your chance to prove it" this line makes perfect sense for the Tabloid Reporter as some follow celebrities' around, reporting and trying to get the latest news (and drama). This line also may give this character a cocky attitude if they do think that they're the "best at digging up dirt" like the Murilo said. Detective Murilo convinces the player to take the phone by saying "In return you'll get the scoop of a lifetime" the player/character of course take the phone. This might mean that the Tabloid Reporter is willing to help someone (who from the junior detective route) we know is famous, for the scoop of a life time.

Junior Detective
(unfinished)