She was born in 1910 in Chicago.  Graduated from Hollywood High School. Lots of stage work in California, started film career with the Christie Company in 1931. Several Buster Keaton and Andy Clyde shorts and the Torchy series for Educational in 1933. No birth year given in trade bio which was written in 1933, but age at that time was given as 23.

As mentioned, Dorothy played the female lead to Ray Cooke in the Torchy series of two-reel comedies that were produced by C. C. Burr and released by E. W. Hammons' Educational Pictures. A report in the May 28, 1932 Hollywood Filmograph noted that she left the Torchy series and signed with Paramount.

After the brief stint at Paramount, she free-lanced. Her career amounted to about twenty films, of which five are B westerns - two with Ken Maynard and one each with Bob Steele, Buck Jones and Gene Autry. The Autry and Jones oaters, GUNS AND GUITARS (Republic, 1936) and SUNSET OF POWER (Universal, 1936) wound up being her last movies.

Dorothy was the sister of Tex Harding (1918-1981) (real name: John Karl Thye), who was a mid 1940s sidekick to Charles Starrett at Columbia.

  Although some of the data is incomplete or inaccurate, the Internet Movie Database (IMDB) has information on Dorothy Dix. As of January, 2015, the IMDb had her birth name listed as Marie Louise Thye. That is incorrect. Marie was Dorothy's older sister: https://www.imdb.com/name/nm0228699/

The Family Search website (free) and the Social Security Death Index (SSDI) provide more on Dorothy Thye (Dorothy Dix) and John Thye (Tex Harding):

• Birth record for Dorothy Dix Thye. She was born July 7, 1910 in Chicago, Cook County, Illinois to Carl Johann Marius Thye (born Denmark) and Mathilde Jensene Sorensen (born Denmark). Has a registration date of October 14, 1942 which indicates a new or updated birth record: https://familysearch.org/ark:/61903/1:1:Q239-QCBB
• 1920 census summary and census takers worksheet - living in Peoria, Illinois are 42 year old Carl M. Thye (born Denmark), his 39 year old wife Matilda J. Thye (born Denmark), 11 year old daughter Marie L. (born Illinois), 9 year old daughter Dorothy M. (born Illinois), 1 year old son John K. (born Illinois), and a servant. They own their home at 2612 Main Street, Peoria, and father Carl's occupation is "Butcher - Butcher shops": https://familysearch.org/ark:/61903/1:1:MJCQ-84W
• 1930 census summary and census takers worksheet - living in Los Angeles, California are 50 year old Carl J. M. Thye (born Denmark), his 47 year old wife Mathelde (born Denmark), 21 year old daughter Marie (born Illinois), 19 year old daughter Dorothy (born Illinois), and 12 year old son John (born Illinois). They own their home at 1545 Laurel Avenue, Los Angeles. Father Carl's occupation is "Proprietor - Meat Market", and there are no occupations listed for his wife and children: https://familysearch.org/ark:/61903/1:1:XCVM-9N2
• 1940 census summary and census takers worksheet - 22 year old John Thye (born Illinois), his 28 year old sister Dorothy (born Illinois), 30 year old divorced sister Marie Lane and her 10 year old daughter Beverly are renting at 7922 Norton, Beverly Hills, West Hollywood, California. John Thye is single; has two years of college; his occupation is "Butcher - Retail meat market", and in 1939, he worked 52 weeks and earned $1560.00. Dorothy is single; completed four years of high school; her occupation is "Designer - Millinery" and she reported no earnings in 1939: https://familysearch.org/pal:/MM9.1.1/K97Z-KXP
• The Social Security Death Index (SSDI) has a record for Dorothy D. Thye, born July 7, 1910, Los Angeles was her last residence, and she passed away on June 15, 2006 in California.

Do not confuse our actress Dorothy Dix with the journalist/writer and newspaper columnist Dorothy Dix (1861-1951) whose real name was Elizabeth Meriwether Gilmer. Her long running "advice to the lovelorn" newspaper column was titled "Dorothy Dix Talks". The Austin Peay State University, Felix G. Woodward Library in Clarksville, TN houses the Dorothy Dix Collection: http://library.apsu.edu/dix/dix.htm