Letter E appears in The Letter Factory. It's the 5th letter of the alphabet. He's voiced by Eric Cummings. They are mint-green, but in Talking Words Factory and Code Word Caper, they are red, except before they got sticky.
Pops (The Secret Life of Pets), Carl Fredrickson (Up), The Head of the Herd (Nellie the Elephant), Grampu (Oobi), Mr. Grouse (The Loud House), Uncle Chuck (Sonic the Hedgehog), Grandpa Squarepants (Spongebob Squarepants), Toadsworth (Super Mario), OJ (TUGS), Toby (Thomas and Friends), Scrooge McDuck, Old Puffer Pete (Chuggington), Don Feinberg (Shark Tale), Lizzie (Cars), Old Pig (Garfield and Friends), Grandpa Boris (Rugrats), Grandpa Abe, Vicar (Wallace and Gromit), Charlie Pincher the Scallion, Grandpa George, Pa Grape and Scooter the Scottish Carrot (VeggieTales), Grandpa Pig (Peppa Pig) and other elders.