Nervous Nellie (Nervous Nelly)

Entry in progress—B.P.
     
Wiktionary: nervous Nellie
Noun
nervous Nellie (plural nervous Nellies)
1. (informal) A person whose personality and behavior are characterized by worry, insecurity, and timidity.
 
(Oxford English Dictionary)
Nervous Nellie  n.  [popularized by use in U.S. politics, especially as applied to Frank B. Kellogg (1856–1937), U.S. politician.] slang (chiefly U.S.) an overly timid, cautious, or fearful person; one who fusses unnecessarily.
1925   N.Y. Herald Tribune 18 Jan. ii. 1/5   [Kellogg] was labeled ‘Nervous Nellie’ by those who were irritated at his maneuvering during the League of Nations fight.
1967   Canadian 2 Sept. 13   They’re window washers and theirs is not a job for nervous nellies.
 
Newspapers.com
24 December 1905, Boston (MA) Sunday Globe, “Household Department,” pg. 31, col. 2:
Nervous Nellie.