The 43-year-old made his debut for Somerset in 1993 and has scored 52 first-class centuries and 7,374 List A runs, more than any other player in the county's history.
Marcus Trescothick has announced that he will retire from the professional game at the end of the season.
The 43-year-old, who made his Somerset debut in 1993, has become one of the county's finest ever players and will call it quits after his 27th and final season as a professional cricketer.
Trescothick, who represented England from 2000 until 2006 and was involved in the historic 2005 Ashes series, has scored 52 first-class centuries and 7,374 List A runs, more than any other player in the county's history.
His record currently stands at 19,654 first-class runs for Somerset at an impressive average of 41.11, and he also holds the record for the most first-class catches (445) for the county.
"It's been an incredible 27 years and I've loved every minute of it," he said.
"However, everything has to come to an end eventually. I've been discussing my future with the club and my family for a while and we felt that now was the appropriate time to make this announcement in order for both the club and I to put plans in place.
Trescothick holds multiple records with Somerset
"There's still a lot of the season left, and I'll be doing everything I can to put in performances for the second XI in order to force my way back into contention for the first team.
"This club, the members and the supporters mean so much to me. There are so many memories that I will cherish forever, and the club will always hold a truly special place in my heart.
"Twenty seven years is a long time, but it’s gone incredibly quickly. I consider myself very fortunate to have had the opportunity to do something that I love for that length of time, and I'm extremely grateful for all the support that I've received throughout this remarkable journey."
As well as a glittering domestic career, Marcus also excelled on the international stage.
His 76 Test matches saw him make his way to over 5800 runs at an average of 43.79, and he was also destructive in the limited overs format, with his 123 ODIs seeing him amass 4335 runs at an average of 37.37.
England fast bowler James Anderson led the tributes to the Somerset legend, whose last international appearance came against Pakistan in September 2006.
"I honestly think he would have had the potential to be the top England run scorer of all time. He was that good in both One-Day cricket and Test cricket," Anderson told Test Match Special.
Somerset Director of Cricket, Andy Hurry, added: "Marcus Trescothick is one of the finest players that this country has ever produced, and his record on the field of play speaks for itself.
"His passion and enthusiasm for the game of cricket is infectious, and his work ethic is phenomenal. He is the absolute personification of what a professional sportsman should aspire to be.
Trescothick had a glittering England career
"Whilst his playing record is there for all to see, what you can't measure is the positive influence that he has behind the scenes. He leads by example in everything that he does, and the way that he goes about his business is second to none.
"Marcus has become part of the very fabric of this club and I'm sure that I speak for everyone associated with Somerset Cricket when I thank him for everything that he has done for the club."
Somerset CCC CEO, Andrew Cornish, said: "I'd heard so many positive things about Marcus before I joined the club, and I was delighted to discover that everything I'd heard was true.
"It's very rare for someone to have a sporting career of such longevity, and that is a testament to the hard work that he puts in behind the scenes.
"We all wish him the very best for the future, and sincerely hope that Somerset Cricket will continue to play a large part in the next chapter of his life."
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