Ingrid

The Snow Queen is a minor character on Once Upon a Time.

Before the Curse
When Prince Hans and his twelve brothers declare war on Arendelle, they seek out an ancient urn that can subdue any magical being. However, Kristoff over hears this and reports it to Elsa. The two seek out to find the urn, but once they do they're stopped by Hans and his brothers. Hans threatens to kill Kristoff if Elsa doesn't hand over the urn. Eventually she agrees to and Hans opens the urn. A while liquid pours out and everyone assume it will consume Elsa, however, it ends up taking the form of the Snow Queen. She turns Hans to ice for calling her a monster and the brothers run away in fear. Elsa is grateful for being saved, so the Snow Queen explains nobody should be trapped in that urn...especially someone as special as her. Eventually they head back to Elsa's castle and the Snow Queen shows signs of nostalgia, especially when noticing a painting of the late king and queen. She reveals to Elsa that the queen was her sister, making her Elsa's aunt. Elsa points out that she never knew of a sister, but the Snow Queen supposes it was to spare her of a hurtful past. When she asks where the queen is now, Elsa reveals she died at sea. She then explains that her sister Anna is missing, so the Snow Queen promises to help find her as that's what family does.

Season 4
After the power cut caused by Elsa's ice wall is fixed and Elsa becomes able to control her magic, she tries to unfreeze the wall... however, she can't. She points out that this is odd because she's the only one with ice powers. Grumpy decides to visit the local ice cream parlour. The woman working inside serves the dwarf and gives him his chocolate ice cream with a smile. He thanks her and questions if she lost a lot of merchandise during the power outage. She points out to him that she didn't lose anything, supposing she must be lucky. She gives him a creepy smile, but Grumpy is oblivious to this. He smiles in return and leaves the shop. After the dwarf leaves the shop, she looks down at a bucket of unfrozen ice cream and with the wave of her hand, she freezes it. She dips her finger in and licks the ice cream off of her finger. She menacingly walks to the fridges at the back of her shop and she leans against them. The moment her back touches the wall, it instantly freezes over. The Snow Queen lets out a little smile.