Tim was born in Seoul, Korea and was raised in Fallston, MD. He enlisted in the Marine Corps in 1992 and completed Marine Corps Recruit Training at Parris Island, SC in June of the same year and subsequently attended Marine Corps Combat Training at Camp Geiger, NC. He was then transferred to Marine Corps Engineer School located at Camp Lejeune, NC. Upon graduation of Engineer School, he was meritoriously promoted to Lance Corporal and was assigned to Engineer Platoon, Headquarters Battery, 10th Marine Regiment. During this time he was promoted to Corporal and attended the Non-Commissioned Officer's Development Course. Corporal Grier served with 10th Marine Regiment until 1995 when he opted to make a lateral move to the M1A1 Tank Technician MOS.

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Then Corporal Grier attended the Basic M1A1 Tank Mechanic Course at the Army Armor Center at Fort Knox, Kentucky. Once he completed this course, he reported to Headquarters and Service Company, 2d Tank Battalion, Camp Lejeune. In 1997 he attended and completed the Marine Corps Advanced Tank Technician’s Course at Aberdeen Proving Grounds, MD. Upon the successful completion of this course, he was assigned to Company B, 2d Tank Battalion where he served as an M1A1 Main Battle Tank Driver, Loader and Gunner, Platoon Sergeant, Platoon Tank Mechanic as well as the Company Ramp Chief.​

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In 1999, then Sergeant Grier was reassigned to tank instructor duty at the Armor Center at Fort Knox, KY with the Marine Training Company, D 1/81. During this time he attended the Formal Schools Instructor Course and the Army’s Combat Lifesavers Course. Sergeant Grier was promoted to Staff Sergeant in 2001 and was reassigned to Charlie Company, 2d Tank Battalion, Camp Lejeune, NC in 2003.

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Staff Sergeant Grier deployed as a Tactical Trainer for the Georgian Train and Equip Program (GTEP) and was deployed to the Republic of Georgia (former Soviet Union) in November of 2003. As a tactical instructor, he assisted in instructing Georgian Troops on a wide variety of skill sets to include: land navigation, small arms and crew served weapons operation and employment, physical fitness and martial arts. He was also responsible for instructing on the maintenance of the Company’s BMP Infantry Fighting Vehicles and T-72 Main Battle Tanks. Staff Sergeant Grier was then redeployed to the United States for duty with Headquarters and Service Company, 2d Tank Battalion.​

 

Staff Sergeant Grier attended the Staff Non-Commissioned Officer’s Course in August of 2004 and was subsequently assigned to Company D, 2d Tank Battalion for duty as the Headquarters Platoon Sergeant. He then deployed with this Company in August of 2005 in support of Operation Iraqi Freedom. During this deployment, Company D conducted combat operations in and around the city  Fallujah, Al Anbar Province, Iraq. Staff Sergeant Grier and his platoon conducted numerous cordon and knock operations, cache sweeps, vehicle checkpoints, mounted and dismounted patrols, logistical resupply, assembly area operations, and detainee and casualty evacuations. Staff Sergeant Grier was promoted to Gunnery Sergeant in December 2005. He redeployed with his Company to the United States in April of 2006.

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Gunnery Sergeant Grier requested and was approved assignment to a Fleet Antiterrorism Security Team (FAST) and attended the requisite Military Occupational Specialty (MOS) courses during 2006. He was then assigned to 2d FAST for duties as Company Operations Chief. He attended the Advanced Course from April to June 2007. In June of 2007, Gunnery Sergeant Grier volunteered to fill vacancy for platoon sergeant, 1st Platoon, 2d FAST. He participated in  operations overseeing the security of special materials related to the fueling of the USS George Bush (CVN-77) at Northrop Grumman Shipyards, Newport News, Virginia. Later that year, he deployed with his platoon to Guantanamo Bay Cuba to assume the fence line security mission. During this time he served as the Watch Commander for the Leeward side of the base.

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In October of 2008, Gunnery Sergeant Grier deployed with his platoon as part of the FAST Deployment Program (FPD) to Naval Station Rota, Spain, where he participated in Operation Noble Shirley, a joint exercise with the Israeli Defense Force (IDF). Subsequently he and his platoon was assigned to a joint mission in Israel related to the security of strategic level infrastructure. His platoon redeployed to Rota, Spain in November of 2008.

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Gunnery Sergeant Grier redeployed to CONUS in March of 2009 and was reassigned as the Platoon Commander for 1st Platoon, 2d FAST. During this time, he task organized the platoon to support multinational training exercises, while embarked aboard the USS Oak Hill and a month long security mission in support of the the honorable Barack Obama, the President of the United States. In June of 2009 he detached from Marine Corps Security Force Regiment and attached, along with a section of his platoon, to HMH-461 and embarked on the USS Iwo Jima for transport to Ghana. During this deployment, he oversaw the security of Air Force One and supporting infrastructure for the duration of the President's visit.

 

Upon his return to CONUS in July of 2009, Gunnery Sergeant Grier was assigned as Platoon Sergeant, 4th Platoon, 2d FAST. During this time he participated in Exercise Tartan Eagle, a bi-lateral exercise with the British Royal Marines. In December of 2009, Gunnery Sergeant Grier was selected to the rank of First Sergeant and executed Permanent Change of Station (PCS) Orders to 3d Light Armored Reconnaissance Battalion, 1st Marine Division, MCAGCC 29 Palms, California in May 2010.

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First Sergeant Grier was assigned to Company B, 3d Light Armored Reconnaissance Battalion for duties as the Company First Sergeant. Upon the Battalion's deployment to Afghanistan in support of Operation Enduring Freedom in October of 2010, First Sergeant Grier assumed the duties of the Remain Behind Team (RBT) Staff Non-Commissioned Officer in Charge, as well as remaining as the First Sergeant for Company B. First Sergeant Grier attended the First Sergeant's Course in February 2011.

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Upon 3d Light Armored Reconnaissance Battalion's return from Afghanistan in May 2011, First Sergeant Grier began the Predeployment Training Program (PTP) Cycle with Company B. He subsequently deployed to Helmand Province, Afghanistan in April 2012. During this deployment Company B successfully executed numerous mounted and dismounted combat patrols, heliborne operations, the retrograde of military equipment and the demilitarization of selected Combat Outposts and Patrol bases. First Sergeant Grier returned to CONUS with Company B in August 2012. First Sergeant Grier reported to Company B, 4th Light Armored Reconnaissance Battalion, Fort Detrick, Maryland for duties, as directed in March of 2013.

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During his assignment to Company B, 4th Light Armored Reconnaissance Battalion he was responsible for supervising the conduct of training, logistics, and the Inspector and Instructor (I&I) staff and reserve company. He also served as the Inspector-Instructor, normally a Major’s billet, for three months. During this time, First Sergeant Grier supervised and participated in the 2013 Frederick, Maryland Toys for Tots Campaign which raised over one-hundred thousand dollars in donated toys  which benefited thousands of needy children in the local area. ​

 

First Sergeant Grier’s personal awards include: a Meritorious Service Medal (with gold star in lieu of second award), a Navy and Marine Corps Commendation Medal (with two Gold Stars in Lieu of Third Award), an Army Commendation Medal, a Navy and Marine Corps Achievement Medal (with two Gold Stars in Lieu of Third Award), and a Army Achievement Medal. 

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Tim Grier retired from active duty in 2014, after serving 22 years. Upon retirement he served as a Marine Instructor with Seneca High School's MCJROTC program for five years and as an Naval Science Instructor (NSI)  with Navarre High School's Navy JROTC program. He started his current role as an NSI in 2020 with the Winter Park NJROTC Program and as the program coordinator for the Emergency Medical Response Program in 2023. He is also a nationally registered and Florida state licensed Emergency Medical Technician (EMT-B) and works in the emergency department of an local hospital as a PRN EMT.  ​

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First Sergeant Grier is married to the former Jennifer Marie Mattingly of Louisville, Kentucky and has four children, Joshua, Joe, Hayden and Alex, and two grandchildren Leila, and Chase.