Black Suit

MiB agents wear suits as their primary uniform. All their clothes including the jacket, pants, ties and leather shoes are all black, hence the name Men in Black while the dress shirts are white. These suits are worn so that when they "neuralyze" a victim, they won't leave any lasting impression or image. These suits were described as "the last suit [an MiB agent] will ever wear", and in the films and television series, these suits are always worn and the agents are all seen wearing them at all times. MiB agents also wear specialized Predator 2 Ray-Ban sunglasses to protect them from their own neuralyzer flash. These sunglasses became popular in the franchise, and sales of these glasses in the market increased over time.

In the films and T.V. series, the MiB have a wide array of disguises that they, and visiting aliens, wear either for their undercover purposes, or for the aliens hidden in the city. Their main purpose though is to make sure that no civilians will ever know aliens are "walking among them", and for the aliens not to spook any civilians.

There are specialized suits that MiB agents use in field missions and investigations. Hazmat suits are seen in the second film, where the agents wore them when investigating Serleena's spacecraft.

Agent K's Suit 1st Generation
Kay started off with the primary MiB suit in 1969 and would continue to wear it in later years. In 1997 during the battle with Edgar the Bug he was swallowed by the giant cockroach in order for him to retrieve his gun which the bug had eaten. He blew the bug from the inside and his suit along with Jay's were covered in entrails. The suit would later be dry cleaned but Kay discarded it after deciding to leave MiB and had Jay neuralyze him so he would reunite with his wife. In 2002 Kay rejoined the MiB and wore the suit again which he currently does to this day.

Agent J's Suit 1st Generation
Jay started off with the primary MiB suit after joining MiB in 1997. During his first battle with Edgar the Bug when Kay blew him up from the inside, the suit along with Kay's were covered in entrails. The suit was later dry cleaned. Jay would wear a new suit after being replaced as head operative for the MiB but later discarded it and would go back into wearing his primary MiB suit. In 2002 the suit was wet after he and Kay were flushed from the MiB Headquarters but it was later dry cleaned. In 2012 during a battle with aliens in a Chinese restaurant Jay would be sometimes be covered in their entrails and the suit would again be dry cleaned.

When Jay time jumped to 1969 to prevent Kay's death he would suffer damage to his suit during a battle with Boris the Animal but would avoid the damage by time jumping back to the beginning of the fight. He currently wears the suit to this day.

Agent J's Suit 2nd Generation
After Kay's retirement, Jay wore a new suit which lacked a tie and the white dress shirt was plain buttoned. The black suit also looked different from the primary MiB suit. Instead of Ray-Ban sunglasses he wore different design ones. He would later discard the suit and would switch back into wearing the primary MiB suit.

Agent L's Suit 1st Generation
Elle had started off with the MiB in 1997 following Kay's retirement. Her suit consisted of the same white dress shirt and black tie like the primary MiB men's suit. She even wore the black pants instead of a skirt like most of the female agents. Elle would later discard the suit after leaving MiB in 2002 and Jay neuralyzed her so she could go back to her former life.

Hazmat Suits
Hazmat suits are used by the MiB to investigate alien activities and to clean and remove alien activity.

Disguise Suit
A specially made suit employed by the MiB in the T.V. series. Unlike other disguises which are big bulky, and immobile, this suit was made to create a faster and quicker desired disguise with a push of a button. Agent J used this in the episode "The Sonic Boom Syndrome". With a push of a button in his tie, an alien disguise engulfs Jay and hid his true form from the aliens.

Heat Resistant Suits
The suits that the MiB agents used in the T.V. Series. First seen in the episode "The Dog Eat Dog Syndrome", these suits were worn for the purpose of protecting the agents from any heat-omitting weapons and environments. The first suit worn were more like the traditional disguises aliens and agents wore. Agent K and Agent J later used a more concealed suit, where they are seen as a transparent tight suit. In Episode 4 of Season 2, the alien Drekk did not know that the protagonist was wearing these suits until he dipped them in a big container of molten metal. The suits protected the agents from Drekk's heat-ray powers, without letting Drekk know they were wearing them.

Stealth Suit
A cloaking device first seen in Episode 5 Season 1. Like what the name says, it is an invisibility suit, resembling a wetsuit, capable of making its wearer invisible, be undetectable by both senses and radar, and emit no signatures. The wearer can also adjust the way it is cloaked so that someone he intends to can detect and communicate with him. It was first worn by the assassin, but although invisible, Agent K soon detected him. Agent J managed to score a direct hit on its wearer but found too late that there was no one in the suit and it was merely a decoy. It was soon put into the MiB possessions and first worn by Agent K.

Trivia

 * In the Will Smith Men in Black music video the background dancers are wearing the MiB primary suits. They are also extras dressed in the suits investigating alien technology.
 * In the Will Smith The Black Suit's Comin (Nod Ya Head) music video the background dancers again are wearing the primary MiB suits.
 * Rapper Pitbull wore a primary MiB suit for the Men in Black 3 music video Back In Time.
 * Frank the Pug was wearing a primary MiB suit when he temporally became Jay's partner but Jay told him to discard the suit. Frank would be seen wearing the suit in the video game MIB: Alien Crisis.