Marcionism, though technically not gnostic, rejected the Hebrew Bible in its entirety.
From the en.wikipedia.org
Marcionism continued in the West for 300 years, although Marcionistic ideas persisted much longer.
From the en.wikipedia.org
Marcionism is discussed in recent textbooks on early Christianity, such as Lost Christianities by Bart Ehrman.
From the en.wikipedia.org
Marcionism was denounced by its opponents as heresy, and written against, notably by Tertullian, in a five-book treatise Adversus Marcionem, written about 208.
From the en.wikipedia.org
Marcionism shows the influence of Hellenistic philosophy on Christianity, and presents a moral critique of the Old Testament from the standpoint of Platonism.
From the en.wikipedia.org
More examples
The Christian heresy of the 2nd and 3rd centuries that rejected the Old Testament and denied the incarnation of God in Jesus as a human
Marcionism is an Early Christian dualist belief system that originated in the teachings of Marcion of Sinope at Rome around the year 144; see also Christianity in the 2nd century. ...
Marcion of Sinope (/u02C8mu0251u02D0ru0283u0259n, -u0283iu0259n, -siu0259n/; Greek: u039Cu03B1u03C1u03BAu03AFu03C9u03BD u03A3u03B9u03BDu03CEu03C0u03B7u03C2; c. 85 u2013 c. 160) was an important leader in early Christianity. His theology rejected the deity described in the Hebrew Scriptures and in distinction affirmed the Father of Christ as the true God. The Church Fathers denounced Marcion, and he chose to separate himself from the proto-orthodox church...
(Marcion (software)) Marcion is Coptic - English/Czech dictionary related to Crum's coptic dictionary, written in C++, based on MySQL, with Qt GUI. Contains many coptic texts, grammars, Greek texts, Liddel-Scott Greek-English lexicon, and others. Can be used as a bible study tool.
(Marcion) (c 110-c 160) Defined canon of Scripture; heretic; God of the OT is different from God of the NT; followers called Marcionites
(Marcion) Second century originator of the heretical idea that there were two Gods, a judgmental, harsh, tyrannical God of the Old Testament, and a loving Father as revealed by Jesus in the New Testament.
Marcion, who died about 160 AD, was a heretic who rejected the Old Testament completely on the grounds that the God there is one of Law while the Christian good news is wholly a gospel of Love. To him, Paul understood this contrast between law and godly love but the Evangelists did not. ...
(Marcion) Gnostic born in Sinope, Pontus. Believed that the God of the O.T. was different from the God of the N.T. Taught that Jesus wasn't born of a woman. Excommunicated in A.D. 144, and refuted theologically by Justin Martyr and Tertullian. This was the first great threat to the early church.