The first Malayali appeared in Indian postal stamp:

Q. The first Malayali appeared in Indian postal stamp:

1. K. Kelappan
2. Sree Narayana Guru
3. Alphonsamma
4. Ayyankali

Answer: Sree Narayana Guru

Narayana Guru (August 28, 1855 – September 20, 1928) was a spiritual leader and social reformer in India. Born into a family of the Ezhava caste in an era when people from such communities were regarded as Avarna. He led a reform movement in Kerala, against the injustice in the caste-ridden society of Kerala in order to promote spiritual enlightenment and social equality.
On 21 August 1967, Narayana Guru was commemorated on an Indian postage stamp of denomination 15 nP. Another commemorative stamp on him was issued by Sri Lanka Post on 4 September 2009. The Reserve Bank of India issued two sets of commemorative coins depicting Guru's image, each valued at ₹5 and ₹100 respectively, on the occasion of his 150th birth anniversary. Narayan Guru became the first Malayali who appeared in Indian Postal Stamp.

Koyapalli Kelappan Nair (24 August 1889 – 7 October 1971) was a founding member and president of the Nair Service Society, a reformer, an Indian freedom fighter, educationist and journalist. During the Indian independence movement, he was the lead figure of the Indian National Congress in Kerala and was popularly known as Kerala Gandhi. After Indian independence, he held various seats in Gandhian organizations. In his honor, India Post released a commemorative stamp in 1990. Saint 

Alphonsa, F.C.C., (born Anna Muttathupadathu; 19 August 1910 – 28 July 1946) was an Indian religious sister and educator. She was the first woman of Indian origin to be canonized as a saint by the Catholic Church, and the first canonized saint of the Syro-Malabar Church, an Eastern Catholic Church based in Kerala. Her feast day is observed on 28 July.
In 1996, Saint Alphonsa was commemorated on an Indian postage stamp of denomination 100 nP.

Ayyankali (also Ayyan Kali) (28 August 1863 – 1941) was a Dalit social reformer who worked for the advancement of deprived, untouchable people in the princely state of Travancore, British India. His efforts influenced many changes that improved the social well being of those people, who are today often referred to as Dalits. Mahatma Gandhi called him the 'Pulaya king'. Indira Gandhi described him as 'India's greatest son'.
12th Aug 2002: Ayyankali was commemorated on an Indian postage stamp of denomination 500 nP.