(spoilers-ish) Currently listed cross-over characters.

(edited, decided to add semblances, cause I thought, why not?)

William 'Terror Billy' James Blazkowicz Wolfenstein(more specifically new order).

[semblance Blazkowicz, name: Aura Reinforcement, capable of taking items like scrap or some food types and converting them into his aura.]

Nagisa Shiota and Karma Akabane Assassination classroom.

[semblance Nagisa, name: Deathly Calm, somewhat similar to Li Ren's semblance projects a sense of calm, however instead of the relaxing calm of Li Ren's semblance, Nagisa's semblance emits a calm of feeling like your standing next to the grim reaper, like Conquerors Haki, or the skill in a lot of rpg's Intimidation.]

[semblance Karma, name: Trickster's Intuition, similar to Ironwood's semblance when active super charges the brain and makes the person very calculative, however Karma's semblance makes him very mischievous and has a greater understanding of traps, tricks, and pranks.]

Rimuru Tempest That Time I Got Reincarnated As A Slime.

[semblance Rimuru, name: Aura Manipulation, do not let the name fool you it is insane, when Rimuru focuses his/her aura then Rimuru can change how the very laws of physics work, but only where they focus the aura, and only for as long as Rimuru wills it to stay like that, any and all modifications to themselves however only reverts when Rimuru wants it to, thus is why Rimuru(unless stated otherwise) has been identified as a them, Rimuru can call upon many feats of amazing powers with Aura Manipulation, however, when Rimuru runs out of aura, then they will fall down and be very hungry, like Saiyan level hunger.]