Misc. Dimensions
Fifth Dimension

Citizens: Mr Mxyzptlk.
First mentioned in: Supergirl: ‘Mr and Mrs Mxyzptlk’.
Notes: Not much is known about the Fifth Dimension, but from the name we can assume that it is more of a multiversal realm than a single universe or planet. Beings from the dimension have the ability to alter reality on a whim and have wormed their way into Earth’s mythology, in the form of genies, imps and pixies.
Speed Force

Citizens: Time Wraiths, Black Flash, Savitar (formerly), Jay Garrick (currently).
First appeared in: The Flash: ‘Fast Enough’.
Notes: On the one hand, the Speed Force is an energy source from which speedsters draw their power. On the other, it is an extra-dimensional realm all of its own, one which spans time and has existed since the Big Bang. It has enforcers known as the Time Wraiths – and recently Black Flash – which punish speedsters who meddle with time. It is also possible to imprison a speedster within the Speed Force.
Hell

Citizens: Satan, Nergal, Astra Logue, Mnemoth, Lamashtu, John Constantine (currently).
First appeared in: Constantine: ‘Non Est Asylum’.
Notes: When the sorcerer John Constantine attempted to exorcise a demon from the human child Astra Logue, it went tragically wrong and Astra herself was sent to Hell – an inter-dimensional realm inhabited by demons and the souls of the damned. Oliver Queen later stated that John Constantine was himself trapped in hell for unknown reasons.

You forgot Hell via Constantine, mentioned in Constantine and Arrow season 4.
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Of course! Thanks for the reminder, updating now.
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