In almost all areas of show business, casting is a very crucial process and right from actors to extras to sometimes even dancers and singers, a casting director is the one who usually puts them together for a project. In the Indian movie business, casting directors have thrived in the public knowledge only in Bollywood and is yet to emerge in other film industries, including the Tamil film industry which is also known as Kollywood.
Seems like that is about to change since a press release from the industry states that a union for casting directors in Tamil Nadu is under consideration and that more than 50 casting directors gathered at Chennai to hold a discussion regarding the same on May 27, 2019.
They have decided that Manoj Krishna who has had 20 years of experience in casting will be heading a their union, the launch of which is expected take place soon, presumably under the affiliation of existing Tamil film bodies.
A union for casting directors would be crucial to ensure proper remittance (which is usually a percentage of the salary of the artists they have brought on board) and recognition in roll credits of a movie.