Leon Rene Yankwich (September 25, 1888 – February 9, 1975) was a United States federal judge.
Born in Iaşi, Romania, Yankwich received an LL.B. from Willamette University College of Law in 1909. He was in private practice in Modesto, California from 1909 to 1916, and in Los Angeles, California from 1916 to 1927, interrupted by service as a Sergeant in the United States Army during World War I, in 1918. He received a J.D. from Loyola Law School in Los Angeles in 1926. He was a judge on the Superior Court of Los Angeles County from 1927 to 1935.
On August 21, 1935, Yankwich was nominated by President Franklin D. Roosevelt to a new seat on the United States District Court for the Southern District of California created by 49 Stat. 508. He was confirmed by the United States Senate on August 23, 1935, and received his commission on August 24, 1935. He served as chief judge from 1951 to 1959, assuming senior status on April 28, 1964. On September 18, 1966, the districts of California were reorganized, and Yankwich was reassigned by operation of law to the United States District Court for the Central District of California. He continued serving in senior status on that court until his death, in 1975.