Yes, there were multiple strains within the early Church that were Unitarian. The article 'Diversity in early Christian theology' goes into some detail on the sorts of ideological movements within the early Church.
The Ebionites are perhaps the earliest, clear example, emphasizing Jesus' humanity, and are an example of 'adoptionism'.
These sorts of views later developed as Monarchianism, and writers in this tradition include Theodotus of Byzantium and Paul of Samosata. Some Montanists were also Monarchians, but not all.
The Monarchians were generally understood to be opposed by Logos theologians, such as Tertullian or Hippolytus. However, Logos theologians were not Trinitarians in the modern day sense.
Arianism (named after the Bishop Arius) is perhaps the most well-known example that is often considered Unitarian. However, Arianism is just one example of what is known as 'subordinationism'. Sometimes subordinationist views are considered as Unitarian, in other cases as proto-Trinitarian.
In summary, you have at least the Ebionites and other adoptionists, the Monarchians (including some Montanists), and the Arians (and more broadly, various subordinationists).
Contemporary Biblical Unitarianism, similar to Socinianism (16th century), would fit into what is called dynamic Monarchianism, a view that is found pre-400.
This image from a talk by Dale Tuggy illustrates the main pre-Trinitarian Christological options from 150-380.