William LaMontagne Jr.

Played by Josh Stewart, Detective LaMontagne was first seen in 2x18 ("Jones") as a New Orleans detective investigating a serial killer case which had initially belonged to his father. Detective William LaMontange Sr. was a detective and had made a breakthrough in the case right before being killed in Hurricane Katrina. The unsub was believed to have suffered the same fate, but when evidence to the contrary arose, Detective LaMontagne took over the case using the work his father had done and a single clue carved on the wall by his father, just before he had died. Detective LaMontagne Jr. called in the BAU to assist him, and they were ultimately successful in capturing the unsub. LaMontagne Jr. spent much of his time on the case choosing to work closely with Agent Jareau.

In 3x17 ("In Heat"), it was revealed that they had been involved for over a year, and in 3x18 ("The Crossing"), JJ called Will to tell him she was pregnant with his child. In the season three finale ("Lo-Fi") Will showed up in New York City while the BAU was on a case, reiterating an off-screen proposal of marriage, and further telling JJ that he would be willing to give up his shield, move to Virginia, and raise their baby. As of early season 4, Will had moved to Virginia, and is apparently now serving as stay-at-home dad to their son, Henry. JJ has not, as yet, canonically accepted the marriage proposal, but they did exchange rings with insets of Henry's birthstone, citrine. He is seen briefly in the 100^th episode getting medicine for Henry with JJ.

Jack Hotchner

His first appearance was in The Fox, when his parents introduced him to the team as a newborn. He was not seen until Machismo and then in In Name and Blood, the last time he will be living with both his parents in the same house.

From then on we see little glimpses of him when his father visits him (Seven Seconds) or when he gets to watch some homemade videos he keeps with him, like in Pleasure is my Business, until Faceless, Nameless when Hotch must say goodbye to him because his mother and him are placed under witness protection after being threatened by Foyet.

His next appearence is again in video format, this time shown to Hotch by Sam Kessmeyer in the episode Reckoner, and we learn his birthday is that day or a near previous one.

In 100 he's seen with his mother in an unknown location when she gets tricked by Foyet to come back to their home, where he's waiting for them. In his eagerness to make Hotch suffer, Foyet allows a lenghty phone call between Haley, Hotch and Jack, and his father gets to tell him to "work the case", a code phrase for him to hide in a bin and wait for his dad to get him, which will be fundamental to save his life.

We see him for the last time in The Slave of Duty, first at his mom funeral and wake and later with his dad at the condo where they are going to live together; in a couple of secuences it's revealed how much he miss his mom and that he thinks his daddy is like Captain America.

Kevin Lynch

Kevin was Garcia's replacement when she was taken off the case in Penelope. He is also a former hacker, but he is also far messier than Garcia. When they met in the end of the episode, they fell in love with each other. They've apparently been dating ever since. They had a date at Garcia's apartment in the beginning of Damaged. In Roadkill, he asked Garcia to apply with him for a high-security job with NASA outside of the country, but she was reluctant to leave the team. The job fell through when Garcia hacked the NASA database to find out where he'd be stationed.

Erin Strauss

She seemed to be under the impression that Hotchner's team was disorganized and posed a threat to the BAU, prompting her to enlist Emily Prentiss to spy on the them (a manoeuvre that backfired when Prentiss resigned her position instead) and to attempt Hotch's removal from the BAU with a pending investigation on his methods. She backed off her attention from the team after experiencing first hand what the team lives with every case in the field (In Name and Blood), but not before making sure that they understood that none of them will ever be able to move up in any higher positions within the FBI.

In the episode "100", she conducted the inquiry into the events surrounding the actual beating to death of George Foyet. She questioned each team member in turn to get to the bottom of the situation, and ensure that "a bloodbath like this never happens again." She finally questioned Hotch, who told her that he believed if Foyet were allowed to get up off of the floor, he would have killed Jack too. She effectively cleared him saying, "That's good enough for me". She also fell away from her cold and spiteful personality that was the norm for most previous episodes and sincerely told Hotch how sorry she was and that "if there is anything you [Hotch] or your son needs..." she would help.

Diana Reid

Like her son, Diana Reid is a genius--though her IQ is never mentioned. She raised Spencer as a single mother after her husband left her due to her schizophrenia. She read to Spencer often, enforcing his already growing intelligence. From her, Spencer learned that the best way to learn is to do "the research" on your own. Through the years, the reading time began to take place in her bedroom, where she spent most of her time on medication.

When Spencer was eighteen, he made the difficult decision to finally have her committed. She now resides in Bennington Sanitarium, where she receives a letter from her son everyday.

Jordan Todd

She was formerly assigned the Counter Terrorism Unit, and has signed on to the BAU team as a temporary replacement for JJ while she is on maternity leave. There have also been hints (4x05 "Catching Out," 4x08 "Masterpiece") that Morgan may be attracted to her, and vice versa. In 4x11 "Normal," Jordan makes a press conference and afterward participates in a raid on the UnSub's home - finding his entire family shot dead. She goes outside and begins to blame herself for the deaths of the family - because of the press conference making the UnSub commit the act. Rossi then comes outside and sits down next to her, comforting her and explaining to her that it wasn't her fault. Jordan then starts crying, and admits that she can't handle the pressures of her new position.

Haley Hotchner

Played by Meredith Monroe, she was the high school sweetheart, and then wife, of Aaron Hotchner. According to 1x22 ("The Fisher King, Part 1"), Hotch spotted her in the hallways and was instantly smitten. Since she was in the school musical production, he joined as well, playing "the worst Fourth Pirate ever." Together they have a son named Jack, born in late 2005. Their marital issues were a running theme early on, specifically Haley's feelings that Hotch devoted more time to the job and the team than he did to his family. It all came to head in the first episodes of Season 3, and by the end of episode 3x02 ("In Name and Blood," also entitled "In Birth and Death"), Haley moved herself and Jack out of the house. At the end of episode 3x03 ("Scared to Death") Hotch mentioned to Morgan that he wasn't sure if Haley was coming back. Hotch was served with divorce papers as he was leaving the office for the day, at the end of episode 3x11 ("Birthright"); at Haley's request, and without retaining a lawyer, he signed them three episodes later (3x14, "Damaged").

Until 5x01, she and Jack were apparently still living in the house she and Hotch had shared. After being mentioned, but not seen, for nearly two seasons, Haley appeared in 5x01 ("Faceless, Nameless"). George Foyet, the Boston Reaper, stabbed Hotch, and stole Haley's address from Hotch's address book. Though she and Jack were soon found unharmed, they were taken into protective custody, intentionally leaving Hotch unaware of their new location. This left Hotch devastated, knowing that he would only be able to see Haley and Jack again once the Reaper was caught. In episode 5-09 "100", Haley is lured to her old home by George Foyet, who has led her to believe that the agent addressed to protect her is dead as well as Hotch. Once in the house with Foyet, he has her call Hotch and she realizes the peril she is in. Hotch tells her to be brave and show Foyet no fear as they tearfully say their goodbyes to each other. Foyet then shoots Haley to death while Hotch and the team listens over the phone.