No, it's not Moe Szyslak or Chief Wiggum, both of whom Azaria voices on The Simpsons. Azaria has filed a suit claiming Bierko has falsely laid claim to a character Azaria allegedly created nearly 30 years ago.
Azaria claims he created the character of "a colorful baseball announcer who speaks with peculiar speech inflections" in 1983, which he later used in a 2010 Funny or Die skit under the name Jim Brockmire. Because the sketch became a viral hit, Azaria claims there's a possibility to develop a feature-length film based on the character.
This is where Bierko comes in. Despite Azaria claiming to have introduced the voice to Bierko after meeting him in 1990, Bierko claims to have either created the character himself, or in collaboration with Azaria — both scenarios that Azaria vehemently denies. Azaria is asking a judge to declare that Bierko has no claim to the Brockmire character.