The Lumas are star-like creatures that appear in most rooms. Their first appearance in Season 1 of In a Locked Room is The Room of Mario Kart, while in Season 2, it's The Wacky Bob-omb Factory. They commonly appear whenever Rosalina calls out for them, but sometimes they appear on their own.
All of them have varied personalities, but all of them help their allies, and especially Rosalina.
In The Room of Super Mario Galaxy, the Lumas played major roles, since the said room's storyline is based on Super Mario Galaxy. Various Lumas appeared in different galaxies and the Comet Observatory itself. A Blue Luma accompanied Yarrow, who is close to it. Different Lumas in different colors gave different abilities, some were trapped, some needed Star Bits. In the end, all Lumas, even the Blue Luma and Yarrow itself, sacrified themselves into the massive black hole caused by Bowser's dying sun to neutralize it. This caused Rosalina to stay in the same room to protect the Comet Observatory until The Lair of the Dark Star, on the time some Lumas were reborn.
The Lumas appear in Season 2's The Wacky Bob-omb Factory, where a Blue and a Yellow Luma make the Mysterious Fusion Reaper disappear all of the sudden with a certain item. They also obtain the Magic Key to destroy the Magic Lock and let Rosalina's cage be destroyed itself.
The Lumas come in different colors, some having abilities.
- Yellow Luma - Transforms into a Launch Star or a Sling Star. This Luma appears commonly the most.
- Blue Luma - Transforms into a Pull Star. Like the Yellow Luma, this colored Luma appears very commonly.
- Pink Luma - Also known as "Hungry Luma", they transform into new planets or galaxies before leaving pink Launch Stars when given enough Star Bits
- Apricot Luma - There is only one known Apricot Luma at the moment. It joined with the Locked Room gang on The Room of Super Mario Galaxy, but like all Lumas, sacrified himself at the end, and is not known to be alive as of now (Since the Blue Luma who accompanied Yarrow replaced his role).
- Green Luma - Very few of them appear, coming from the Planet of Trials, or at other places.
- Turquoise Luma - Also known as "Lumalee", they sell Life Mushrooms and 1-Up Mushrooms, but are never seen doing so.
- Red Luma - Gives anyone the Red Star, which makes them fly freely temporarily.
- Purple Luma - Gives information about the Prankster Comets (Lumacomète) and appear in cold places in general. The known Purple Luma, Lubba, has yet to appear.
- Black Luma - Potentially the rarest color (not counting the lone Apricot Luma), they give guides to anyone. The only known Black Luma so far is Polari.
- Orange Luma - Their abilities are completely unknown and have yet to properly appear.