H. Jerome Keisler was a longtime professor at the University of Wisconsin, Madison, whose research included model theory and nonstandard analysis. He is known for extending the Henkin construction to what are now called Henkin-Keisler models.
C. C. Chang, Professor Emeritus of Mathematics at UCLA, also focused on model theory and proved the ordinal partition theorem. Chang's conjecture is named after him, as is ccc forcing.