Jean Harlow only lived for 26 years, but her name is one of the most famous in Hollywood. A symbol of every man's desire, the original blond bombshell, and the inspiration for Marilyn Monroe. Of course, she started out as an extra and bit actress.
She made 39, 40 or 41 movies over nine years, it is not clear as people try to recognize her as an extra on the screen. Accurate records of extras weren't kept in those early days.
In an early film in 1928 she worked with Charley Chase and director James Parrott at Hal Roach Studios. She appeared in four films with Laurel and Hardy; Liberty, Double Whoopee and Bacon Grabbers in 1929 and Beau Hunks in 1931 (but only as Ollie's girlfriend in a still photo). That same year she made City Lights with Charlie Chaplin.
There were several films with Edgar Kennedy, and seven films with writer/director Leo McCarey who worked with Stan and Ollie. She must have been on contract with Hal Roach.
She also worked in the early days with Clara Bow (The "It" Girl), Jean Arthur, Charles "Buddy" Rogers, Maurice Chevalier, Jeanette McaDonald, and was uncredited in almost all of them. She made Love Parade with director Ernst Lubitsch in 1929. She worked with all of these stars BEFORE she became famous.
Finally in 1930 she had a larger part in the Howard Hughes World War I movie called Hell's Angels. She changed her name several times through her career, appearing early under her real name Harlean Carpenter, then as Jean Harlowe, and then dropping the "e" to Harlow.
You can see how much you can learn about bit players when you look at their early careers. Some make it big, and some end up playing bit parts all their lives, like Leonard Bremen. Jean Harlow was a lucky one for a short while. She was engaged to William Powell when she died.