Endres started with the Fleischers in 1930 as an opaquer (sitting next to Jack Mercer) and worked his way up through the ranks to animator. (and eventually director - though not on any Popeye shorts) His first Popeye animator credit was on 'Stealin' Ain't Honest' released in 1940 although he has uncredited animation in 'It's the Natural Thing To Do' released in 1939. Before that he animated for Myron Waldman's unit on the Color Classics and Betty Boop cartoons.
I wonder why Endres was chosen to animate for Steve Muffati on the first Superman cartoon produced at the Fleischers. His cartoony animation style is noticable in contrast with the realistic styled characters. (scenes of Lois putting on the aviator's cap and the plane flying into the distance, etc.) It's a strange mixture for sure.
Absent from the Famous Studio during the war years, Endres served in the Navy during World War 2. The last Popeye cartoon he animated on before his departure was 'Me Musical Nephews' and the first Popeye cartoon he animated on upon his return to the studio was 'I'll Be Skiing Ya'.
During the last years of Popeye, Endres' work went through a marked style change. His Popeye looked different and his animation was stiffer than earlier efforts. I wonder what happened to cause him to change his animation style.
Endres' animation on Popeye was exclusive to the Johnson unit until the shorts ceased production.
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Stealin' Ain't Honest - 1940
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Doin' Impossikible Stunts - 1940
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Flies Ain't Human - 1941
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Scrap the Japs - 1942
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Me Musical Nephews - 1942
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I'll Be Skiing Ya - 1947
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The Royal Four Flusher - 1947
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Wotta Knight - 1947
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Safari So Good - 1947
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All's Fair at the Fair - 1947
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Robin Hood-Winked - 1948
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How Green Is My Spinach - 1950
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Quick on the Vigor - 1950
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Punch and Judo - 1951
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Cookin' With Gags - 1954
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Spooky Swabs - 1957