Graphs have applications in all areas of science and therefore the interest in Graph Theory is increasing everyday. They have applications in Chemistry, Pharmacology, Anthropology, Biology, Network Sciences etc. In this paper, Graph theory is connected with algebra by means of a new graph invariant Ω and define triangular graphs as graphs with a degree sequence consisting of n successive triangular numbers and use Ω and its properties to give a characterization of them. We give the conditions for the realizability of a set D of n consecutive triangular numbers and also give all possible graphs for 1 ≤ ≤ 4 .