The Nepal Communist Party, abbreviated NCP (Nepali: नेपाल कम्युनिष्ट पार्टी, pronounced [neˈpal ˈkʌmjunisʈ ˈpa(r)ʈi]) was founded on 17 May 2018, from the unification of two leftist parties, Communist Party of Nepal (Unified Marxist–Leninist) and Communist Party of Nepal (Maoist Centre). The unification was completed by the Party Unification Coordination Committee, after eight months of negotiation. The two predecessor parties subsequently dissolved, making way for the new united party. The party retained the electoral symbol of the CPN (Unified Marxist–Leninist), the sun.

The party was the largest political party in the House of Representatives, National Assembly and in all provincial assemblies except No. 2. K. P. Sharma Oli, Prime Minister of Nepal since 15 February 2018, and former Prime Minister of Nepal Pushpa Kamal Dahal both served as the chairmen of the party. After internal conflicts in the party and the dissolution of parliament, the party splintered into two major factions. On 8 March 2021, Nepal's Supreme Court stated that the allocation of the name "Nepal Communist Party" upon the merger of the CPN-UML and CPN (Maoist Centre), and by extension the merger itself, was void ab initio, as the name was already allotted to a party led by Rishiram Kattel, and that the NCP stood "dismissed". Upon the ruling, the two predecessor parties were revived in their original state immediately prior to the merger, although should the two wish to merge again with proper procedure being followed, it would be fully allowed.