Coba jelasin Komandan dari Batalyon Infanteri Mekanis 121 dong

Letkol Inf Yansen Saragih (1958 - 1959)

Letkol Inf Selamat Ginting (1959 - 1960)

Mayor Inf Agus Husin (1960 - 1961)

Letkol Inf Bahari Hasibuan (1961 - 1962)

Letkol Inf Leidin Girsang (1962 - 1963)

Letkol Inf Firman Siregar (1963 - 1967)

Letkol Inf A. Lumbanraja (1967 - 1968)

Mayor Inf Azuan Effendi (1968 - 1971)

Mayor Inf Marzuki Erman (1971)

Mayor Inf Rade Mulyadi (1971 - 1972)

Mayor Inf Achmad Nurhaman (1972)

Mayor Inf Achmad Wahid (1972 - 1973)

Mayor Inf Yusni Thamrin Yusuf (1973 - 1975)

Mayor Inf Fahruddin Abdul Salam (1975 - 1976)

Mayor Inf Maksum Atmawijaya (1976)

Mayor Inf R. Karyono (1976 - 1979)

Letkol Inf Syaiful Anwar (1979 - 1982)

Letkol Inf Joko Sugiharto (1982 - 1983)

Mayor Inf Kusmahadi (1983 - 1986)

Mayor Inf Suharto (1986 - 1988)

Mayor Inf Farid Ali (1988 - 1990)

Letkol Inf Bakti Tamsil Tarigan (1990 - 1993)

Mayor Inf Hari Suharto (1993 - 1995)⭐⭐

Mayor Inf Ira Suparmo (1995 - 1996)

Letkol Inf Pratimun (1996 - 1997)⭐⭐

Mayor Inf Deni K. Irawan (1997 - 1999)⭐⭐

Letkol Inf Toto Endraharto (1999 - 2000)

Letkol Inf Supartodi (2000 - 2001)⭐⭐

Letkol Inf Sungkono (2001 - 2003)

Mayor Inf Fachri (2003 - 2004)⭐

Letkol Inf Frans Thomas (2004 - 2006)

Letkol Inf Herry Christanto (2006 - 2008)

Letkol Inf Dwi Tugas Irianto (2008 - 21 Juli 2010)

Mayor Inf Leo Agung Priyo Soembodo (21 Juli 2010 - 5 November 2011)

Letkol Inf Ayub Akbar (5 November 2011 - 29 Juli 2013)

Mayor Inf Setia Asmara (29 Juli 2013 - 2015)

Mayor Inf Andrian Siregar (2015 - 17 November 2017)

Mayor Inf Imir Faisal (17 November 2017 - 30 Agustus 2019)

Letkol Inf Wisnu Joko Saputro (30 Agustus 2019 - 2021)

Letkol Inf Ery Partahi Hamonangan Siregar (2021 - 2023)

Mayor Inf Medwin Sangkakala (2023 - Sekarang)