The answer is Tiamat. Tiamat is a sea serpent Titan who feeds on electricity. The film describes her as extremely territorial and deadly, and Monarch even classifies her as a "Destroyer" Titan.

Now, Legendary Comics is bringing fans Monsterverse Declassified, a new anthology coming to comic shops and bookstores this spring. There are not many details on the creative team or direction yet, ...

The breakdown continues, “Discover the legacy of TIAMAT that lives on through ancient fables and futuristic technology. And live a day in the life of the tiniest Titan of them all, TITANUS… DOUG.