Source: dccomics.com

4. Jim Gordon

James W. Gordon was a police officer's police officer. The father of James Gordon, Jr. (by birth) and Barbara Gordon (by adoption), James, Sr. was a Gotham cop until he killed a dirty cop and was transferred to Chicago to cover it up (the kid of said dirty cop would eventually grow up to become The Wrath).

After exposing MORE corruption, he was transferred right back to Gotham, this time as a Lieutenant. Around this time, Batman popped up, and although they didn't get along at first, they would eventually learn to work together, mostly through giant rooftop flashlights.

Third in their partnership was District Attorney Harvey Dent. That is, until Harvey went all murdery and started basing said murders on his own coin flipping. But after that, the Gordon/Batman relationship only strengthened. Gordon resigned from the GCPD after getting shot, but later returned to the force.

Then there was a reboot, and then Gordon became GCPD-approved Batman for a while, "˜cause Batman got Endgamed, and then he was just a cop again. *Deep breath in.*