Mr. Met was first introduced on the cover of game programs, yearbooks, and on scorecards in 1963, when the Mets were still playing at the Polo Grounds in northern Manhattan. Comic book artist Al Avison was at least one of the artists who contributed to the character's design. When the Mets moved to Shea Stadium in 1964, fans were introduced to a live costumed version, portrayed by team ticket office employee, Daniel J. Reilly. Mr. Met is believed to have been the first mascot in Major League Baseball to exist in human (as opposed to artistically rendered) form. He was also the first person on the Mets to be represented by a bobblehead doll.
In the 1960s, Mr. Met occasionally appeared in print with a female companion, Mrs. Met (originally called "Lady Met"), and less frequently with a group of three "little Mets" children; the smallest was a baby in Lady Met's arms. Mrs. Met was debuted in a short lived live costumed form in 1975 before being reintroduced in 2013.
In the mid-1970s, the Metropolitans franchise began to dissolve the Mr. Met mascot. In 1976, he appeared on the cover of the New York Mets Official Yearbook. After that time, he was not utilized in their advertising and he remained absent for almost 20 years. He was phased out prior to the upsurge in mascot popularity caused by The San Diego Chicken and the Phillie Phanatic in the late '70s. In 1979, after the Mets discontinued use of Mr. Met, the team briefly experimented with a new mascot named "Mettle the Mule" that was a living animal that would parade along the foul lines prior to a game.
In 1992, long time Mets fan, Lois Kaufmann of Queens, New York, wrote a compelling appeal for his reinstatement and asking the Mets to resurrect the mascot. The team did not act quickly or grant Lois her request to be Mr. Met. However, in 1994, they did follow her advice and revived Mr. Met as part of a promotion with Nickleodeon. After a long absence, Mr. Met was quickly re-embraced by New York Mets fans and has since remained a constant part of the franchise.
On April 14, 2002, the Mets held a birthday party for Mr. Met at Shea Stadium. It was attended by costumed mascots from all around Major League Baseball and by Sandy the Seagull, mascot of the Brooklin Cyclones, a Mets farm team.
In the 2003 season, first baseman Tony Clark was the first Mets player ever to wear #00, Mr. Met's number. In June of that season, he switched to #52 when Queens schoolchildren asked him what had happened to Mr. Met.
On September 14, 2007, Mr. Met was elected into the Mascot Hall of Fame.
Beginning on August 14, 2009, throughout their series against the San Francisco Giants, the Mets wore throwback jerseys featuring a Mr. Met patch on the right sleeve.
Currently, Mr. Met can be seen at Citi Field during and after games. He is usually found near Mr. Met's Kiddie Field where fans can meet and pose for pictures with him. He can be rented for special events and private parties. Mr. Met is also featured on Mets Money, which are $1, $5 and $10 denomination gift certificates accepted at concession stands and souvenir shops at Citi Field. The design is somewhat reminiscent of standard U.S. currency, but instead features images of Mr. Met attired and posed similarly to the historical official (Washington, Lincoln or Hamilton) featured on the respective bill.
The second version of the Mr. Met head is now on display at the New York Mets Hall of Fame and Museum at Citi Field. He Is "Baseball's Favorite Mascot".
In 2013, the Mets introduced batting practice caps featuring Mr. Met on the front. In 2014, a Mr. Met sleeve patch is featured on the Mets' blue alternate home and road jerseys.
Mr. Met has been portrayed by many people over the years. Dan Reilly was the first person to wear the Mr. Met costume, starting in 1964. According to the March 20, 2006, issue of The New Yorker, Reilly is working on a book about his experiences with the team, to be called The Original Mr. Met Remembers.
Mr. Met was portrayed from 1994 through 1997 by AJ Mass, currently a fantasy sports writer for ESPN and author of the book How Fantasy Sports Explains the World, published in August 2011. Matt Golden portrayed Mr. Met from 1999 to 2011.
In a 2003 This is SportsCenter ad, when the show ends, everyone rushes out of the studio, creating a massive traffic jam. It then shows Mr. Met and Mrs. Met driving home on the freeway (with the Met children in the back), with Lady Met subtitled as saying they were glad to get out early. The New York Mets theme song, "Meet the Mets", is on their car radio. (A shorter version with just the Mets family has Mrs. Met accusing Mr. Met of making eyes at one of the female ESPN sportscasters.)
In 2009, Mr. Met appeared in another This is SportsCenter ad, which Mr. Met is talking with Stuart Scott at a microwave. When Josh Hamilton shows up to use the microwave, Mr. Met angrily gestures at him and walks away. Hamilton is confused until Scott reveals that some of the balls Hamilton hit in the 2008 Home Run Derby were actually relatives of the mascot.
In 2007, Mr. Met became a spokesman for MTA New York City Transit, appearing on several advertisements and safety messages within the New York City Subways and buses.
He was also featured in commercials for MLB 06: The Show, a video game for Sony's PlayStation 2, where a camera crew followed him around as he performed his daily duties, such as buying coffee and picking up his laundry. In 2010, he began appearing in commercials for Citi Bank that aired during Mets broadcasts, inducing Mets fans to join him in a "Let's Go Mets" cheer during mundane activities such as business meetings.
He has his own Build-A-Bear Workshop store, but instead of at Citi Field, it's located at the Mets' flagship store on Manhattan's Fifth Avenue.