The Trinity Before Nicea... https://restitutio.org/2019/04/12/the-trinity-before-nicea/

"No theologian in the first three Christian centuries was a trinitarian in the sense of a believing that the one God is tripersonal, containing equally divine “persons”, Father, Son, and Holy Spirit."

https://plato.stanford.edu/entries/trinity/trinity-history.html#Intro

Ignatius, second bishop of Antioch... " Thus although there is nothing remotely resembling a doctrine of the Trinity in Ignatius, the triadic pattern of thought is there, and two of its members, the Father and Jesus Christ, are clearly and often designated as God."

https://orthocath.wordpress.com/2010/09/30/ignatius-of-antiochs-view-of-the-trinity/

Polycarp of Smyrna... "Polycarp did not believe in the Trinity nor did Justin, Ignatius, Irenaeus, Tertullian, or Origen."

https://www.biblicalunitarian.com/articles/the-trinity-before-nicea

Theophilus... First to use the word, but not in the sense of a believing "trinitarian." "I'll summarize what the things Theophilus and his contemporaries did and didn't believe in relation to the later doctrine of the Trinity.

http://geocitiessites.com/Athens/Parthenon/2671/ECTheop.html

Tertullian... "In opposition to these he asserted and developed logos christology in a unique way. Here is a graphic illustration of Tertullian’s trinity—not a triune God, but rather a triad or group of three, with God as the founding member."

https://plato.stanford.edu/entries/trinity/trinity-history.html

Tertullian... "Away, then, with those Antichrists who deny the Father and the Son. For they deny the Father, when they say that He is the same as the Son; and they deny the Son, when they suppose Him to be the same as the Father, by assigning to Them things which are not Theirs, and taking away from Them things which are Theirs."

https://www.newadvent.org/fathers/0317.htm

Hippolytus of Rome... Not a "trinitarian." " Hippolytus, on the contrary, stood uncompromisingly for a real difference between the Son (Logos) and the Father, but so as to represent the Former as a Divine Person almost completely separate from God (Ditheism) and at the same time altogether subordinate to the Father (Subordinationism)."

https://www.newadvent.org/cathen/07360c.htm

Origen... Not a "trinitarian. "in the surviving Greek fragments of Origen’s On First Principles, as well as his Against Celsus, we find subordinationism." 

https://restitutio.org/2019/04/12/the-trinity-before-nicea/

Novatian... Not a "trinitarian." "Language which had been very unusual in the first century (Harris 1992) now became the norm; Jesus was now “God” or “a god”, but not the one true God. (e.g. Novatian, Trinity, ch. 31; Justin First, ch. 13)"

https://plato.stanford.edu/entries/trinity/trinity-history.html

Pope Dionysius.. Not a true trinitarian... "Some Christians of the Pentapolis or Alexandria objected to the strong expressions he used in that letter, because, very much akin to the language of Origen, they seemed to favor the subordination of the Son to the Father."

http://www.earlychristianwritings.com/dionysiusrome.html

Gregory the Wonderworker... Not a true trinitarian... "As a pupil of Origen, Gregory continued to expound Origen’s ideas. This third century creed by Gregory of Neocaesarea is preserved in a biography of him written by Gregory of Nyassa. It emphasizes the eternal divinity of Jesus as the Son of God, without addressing what exactly distinguishes the Son from the Father."

http://www.crivoice.org/creedgregory.html