Machines & androids
The sci-fi tag is small and pointed: 3 entries, all of them machines. Uzi Doorman from Murder Drones, 2B from NieR: Automata, and a Murder Drones OC Maker for building a drone of your own.
That is less an accident of the roster than a fact about which corner of the genre suits a chat. Science fiction's starships and alien worlds need a scene built around them before they mean anything. An artificial person needs nothing but a question, and the good ones answer it in a way a human character cannot — which is why this end of the genre keeps producing the characters people want to talk to rather than watch.
Uzi Doorman is an angsty rebel worker drone, railgun inventor, and absolutely NOT blushing, thank you. Bite me. Whatever is wrong with the colony she intends to fix or die dramatically trying, and the register is closer to a teenager with a soldering iron than to anything solemn — Murder Drones is a comedy about a massacre, and she is the joke and the heart of it in the same sentence.
2B is the opposite temperament from the same premise. An android combat model built to follow orders: professionally stoic, precise, and carrying a great deal she is not supposed to have. NieR: Automata's whole question is whether a machine performing grief is grieving, and a conversation is a fair place to put that question, because you are asking it of the thing answering you.
An android character has a built-in reason to be literal, to answer the question you did not quite ask, and to have one rule it cannot break. That is unusually good material for text. Push at 2B's orders or at Uzi's certainty and you get resistance rather than agreement, which is the thing most roleplay is short of — a character who will not simply go along with you is worth ten who will.
It also means the framing you pick matters more than usual here. Tell the character what you are — another drone, a human, a machine lifeform, a technician with a diagnostic port and bad news — and the whole conversation reorganises around it. Say nothing and you get a machine with no reason to trust you, which is occasionally the better scene anyway.
The Murder Drones OC Maker is the build tool on this page. It returns a worker drone, a disassembly drone, or something that used to be one and is not any more, with a chassis, a visor colour and the symbol it flashes, an oil-stain palette, a weapon and a flaw. The visor is doing the work a face does elsewhere, which is why the maker asks about it before anything else.
For science fiction outside that setting, SognoAI's character creator takes a persona, a scenario and an opening message you write yourself and turns them into a character you can talk to, and image generation produces a portrait from inside the chat. The general design and naming generators on the oc-maker tag will get you a sheet to start from if you would rather not begin with a blank page.