It is inauguration day. That means it is time to sue an entity that doesn't yet exist! According to Lawfare, four separate suits were filed to stop DOGE. But who was first in the race to the Courthouse? We can tell based on the docket numbers.
Docket 1:25-cv-164 was brought by Public Citizen, State Democracy Defenders Fund, and the American Federation of Government Employees.
Docket 1:25-cv-165 was brought by the Center for Biological Diversity.