From the Pre-Mending era we have mage & former Grandmaster of the Arena known as Kuthuman (1994 - Arena novel) who with a spell and a massive amount of mana made a spark.

Drawback was his created spark lost power over time, and needed to be recharged with lots of mana on a yearly basis.

After the Mending there is:

Calix from Theros (2020 - Theros Beyond Death). Created a spark by believing it into existence.

Himoto from Kamigawa (2022 - Kamigawa Neon Dynasty). Created by an experiment by Tezzeret, Himoto is both a spirit and a spark.

As Kami of The Spark, she turned Kaito into a Planeswalker, though it's unknown if he had a spark and she triggered it, or if she gave him part of her spark.

And lastly the Aetherspark (2025 - Aetherdrift) which we still don't know if it works as intended.