Agent Makes Big Claim Against Big Bang Theory Star

Diverse Talent Group filed docs in L.A. County Superior Court last week ... claiming Kunal owes his agency $100,000 in unpaid commissions for getting him the acting gig -- a bill that goes back to September 2011.

The lawyer for DTG tells TMZ, the agency repped Kunal when he got the job in 2007 -- and the actor faithfully paid the piper ever since, but for some reason ... he stopped coughing up dough last year.

Now, DTG is suing for its money, which it believes exceeds $100k.