Nambiathusseril Varkey John (14 October 1927 – 17 July 2014), better known by his screen name Sasikumar, was an Indian film director who worked in Malayalam cinema.

While in Merryland he worked with many renowned actors of that time, including T. K. Balachandran, Prem Nazir and Thikkurissy Sukumaran Nair.

The first independent film directed by Sasikumar was a documentary, namely ONAKKAZHCHA for Fertilisers and Chemicals Travancore Limited (FACT) regarding the use and effectiveness of fertilizers in agriculture.

As a result, a dejected Sasikumar decided to give up film direction and return to Kerala to join his father's oil mill business.

It was Prem Nazir who encouraged him to return to Chennai where he directed the commercial film Jeevitha Yaathra which became a major hit.

Sathyan, Prem Nazir, Adoor Bhasi, S. P. Pillai, Madhu, Jose Prakash, Sheela, Vijayasree, K.R.Vijaya, Sharada, Vidhubala, Lakshmi, Sreelatha, Jayabharathi, Sreevidya, Nanditha Bose, Unni Mary, Kamal Haasan, Mammootty, Sukumaran, Soman, Ravikumar, Jayan, Vincent, Sobhana, Shankar, Mohanlal and Suresh Gopi all acted in his films.

It was Sasikumar who introduced a new sophisticated villain to the Malayalam film world in the form of "Silver Head" enacted by Jose Prakash in Love in Kerala (1968).

Sasikumar acted in small roles in films like Thiramala, Sreerama Pattabhishekam, Velakkaran, Thommante Makkal, Seetha, Snehadeepam, Umma, Bhakta Kuchela, Snapaka Yohannan, Kattumaina, Visappinte Vili, Oral Koodi Kallanayi etc.

His assistants P. G. Viswambharan, G. Prem Kumar, Crossbelt Mani, Baby, Thampi Kannanthanam, and Asokan became successful independent directors later on.

The Kerala state Government honoured him in the year 2013 by conferring on him the coveted J. C. Daniel Award for his manifold contributions to the Malayalam cinema.