During the fourth season he suddenly resigned as Security Chief; he then begins working for Edgars Industries on Mars, one of the largest corporations on the planet.
On the positive side he is loyal, trustworthy, brave, shrewd, thorough in his job duties, and a tough and skilled soldier with small arms, in hand-to-hand combat, or in the cockpit of a Starfury fighter.
He possesses a lively sense of humor, enjoys watching old twentieth-century cartoons such as "Daffy Duck" (Duck Dodgers in the 24½th Century) who is referred to as a "household god of frustration" for Garibaldi in a conversation between Zack Allan and G'Kar, loves twentieth-century motorcycles, and generally has an easygoing, laid-back personality when he's not on duty.
However, he can also (ironically, given his suspicious nature) be too trusting of close friends and aides, and his tendency towards alcoholism and self-destructive behavior is a constant struggle for him throughout the series.
Of the major characters on Babylon 5 Garibaldi is in many ways the most "down-to-earth" and "ordinary"; he often sides with the working-class humans on the station and in turn is considered by them to be a kindred spirit.
This honesty, and his refusal to "play along" with policies and actions he knew were illegal, got him into difficulties with corrupt officials on more than one occasion.
However, his experiences led to a certain amount of distrust and dislike of pompous high-ranking officers, a fact which often got him into trouble with his superiors.
Because of his bouts with alcohol & PTSD, he's often seen as a sympathetic character to fellow veterans of the war, giving them wide latitude when they commit minor infractions on his watch as B5 Chief of Security.
He managed to keep his alcoholism under control (he is often seen refusing free liquor and drinking water instead), and became well-liked and respected by the security forces that he commanded.
During Garibaldi's second year, he discovered a plot to assassinate Earth Alliance President Luis Santiago.
Franklin explained that he felt that a person in such circumstances could come to a point where they'd lose the will to live, and the body would then stop cooperating.
When President Clark began turning the Earth Alliance into a dictatorship, and with the reemergence of the Shadows, Garibaldi became the liaison between Babylon 5 and the Anla'Shok, or Rangers, upon receiving a message from Sinclair, who had since become the leader of the organization upon being posted to Minbar, a side duty that was known to the Rangers and a select few Sinclair felt he could trust, including Garibaldi.
When Nightwatch, a sinister police force created by President Clark to expose and arrest "traitors to Earth", began to infiltrate station security, Garibaldi refused to cooperate with them.
When Sheridan withdrew Babylon 5 from the increasingly fascist Earth Alliance in the episode "Severed Dreams", the station was soon attacked by a fleet of EarthForce warships loyal to President Clark.
But when the actor Jerry Doyle broke his arm during filming, in the next episode he was shown wearing a sling - Garibaldi explained this as that he fractured his wrist and forearm during the fight, but had initially not thought it bad enough to let Dr. Franklin put it in a cast.
When Sheridan detonated the White Star - which had two fusion bombs on it - over the Shadow capital city, the force withdrew.
Alfred Bester diverted Garibaldi's transport to a Psi-Corps facility of his choosing, and spent the next two weeks carefully reprogramming him to uncover a conspiracy against the telepaths.
He resigned from his job as chief of security to work as an independent investigator over the next several months, helping people find what they had lost in the war.
Garibaldi gained some initial trust in the organization by smuggling several valuable items destined for Mars through Babylon 5 customs.
Using his influence, he got Lyta Alexander released from jail and offered to funnel money and resources to her to finance her fight against the Psi-Corps.
With the new Head of Covert Intelligence Tessa Holloran - the former Number One of the Mars resistance - Garibaldi was able to find out all sorts of useful information about the board.
He told Sheridan and Delenn that he had never expected to live that long—he had been sure for a long time that his tenure on Babylon 5 would end with him face down somewhere in Brown Sector.
While there had been a great deal of problems integrating Earth and Minbari technology, two vessels were built, the prototypes Victory and Excalibur.
After Sheridan is taken from the galaxy by Lorien, Garibaldi makes one last trip to Babylon 5, for the shutdown ceremony, and takes a piece of the station—a shot glass bearing the station's logo—with him before leaving for the last time.
However, Daniel, a member of an Orwellian faction seeking to sever Earth from the Interstellar Alliance in the face of a looming civil war, brings back holographic recreations of Garibaldi, Sheridan, Delenn, and Franklin.
He begins reprogramming the recreations to re-enact distorted and propagandized versions of historical events so that he can convince others that the Interstellar Alliance is (and always has been) evil.
During a break between recordings the Garibaldi recreation reveals what he's done to Daniel, just seconds before the government launches a preemptive attack on the rebel facilities.
The holographic studio is destroyed shortly thereafter, prematurely starting a civil war but denying Daniel's organization the potentially catastrophic propaganda material they sought.
[3] As Jerry Doyle died in July 2016, the Michael Garibaldi character will not make any further appearances in any future Babylon 5 movies or television series.
[4] Garibaldi's flaw of being a recovering alcoholic has been described as being quite personal for the actor who played him, who shared similar history in his real life.