The novel has many quotes/exchanges that either say or imply that Bob Ewell is a "horrible character." Below I have selected a few that seem particularly fitting.
CHAPTER 17 -- Bob Ewell is a racist full of hatred. His identification of Tom Robinson at the trial provides evidence.
__[BOB EWELL] "...Well, Mayella was raisin‘ this holy racket so I dropped m'load and run as fast as I could but I run into th' fence, but when I got distangled I run up to th‘ window and I seen—[He stood up and pointed his finger at Tom Robinson]...ni_ ger yonder ruttin' on my Mayella!"
CHAPTER 23 -- Through Scout, as narrator, Miss Stephanie Crawford provides a description of an incident between Bob Ewell and Atticus that took place after the trial . This description speaks volumes about Bob Ewell.
__[SCOUT as narrator] "According to Miss Stephanie Crawford, however, Atticus was leaving the post office when Mr. Ewell approached him, cursed him, spat on him, and threatened to kill him... Miss Stephanie said Atticus didn't bat an eye, just took out his handkerchief and wiped his face and stood there and let Mr. Ewell call him names wild horses could not bring her to repeat. Mr. Ewell was a veteran of an obscure war; that plus Atticus's peaceful reaction probably prompted him to inquire, 'Too proud to fight, you ni_ ger-lovin‘ bastard?' Miss Stephanie said Atticus said, 'No, too old,' put his hands in his pockets and strolled on..."
CHAPTER 27 -- Link Deas has given a job to Tom Robinson's widow, Helen. Bob Ewell remains a menacing, evil figure.
__[SCOUT as narrator] "Helen went to work next morning and used the public road. Nobody chunked at her, but when she was a few yards beyond the Ewell house, she looked around and saw Mr. Ewell walking behind her... Mr. Ewell kept the same distance behind her until she reached Mr. Link Deas's house. All the way to the house, Helen said, she heard a soft voice behind her, crooning foul words. Thoroughly frightened, she telephoned Mr. Link at his store, which was not too far from his house. As Mr. Link came out of his store he saw Mr. Ewell leaning on the fence..."
CHAPTER 29 -- After Bob Ewell has attacked Scout and Jem as they walk home at night from the school Halloween pageant; after Arthur "Boo" Radley has helped the children escape from Bob Ewell; and after Sheriff Tate has told Atticus that "Bob Ewell's lyin‘ on the ground under that tree down yonder with a kitchen knife stuck up under his ribs. He's dead, Mr. Finch", Scout remembers something.
__[Scout] "Somehow, I could think of nothing but Mr. Bob Ewell saying he'd get Atticus if it took him the rest of his life. Mr. Ewell almost got him, and it was the last thing he did."
CHAPTER 29 -- Atticus and Sheriff Tate have a revealing exchange about Bob Ewell.
__[SHERIFF TATE] "Don't like to contradict you, Mr. Finch—[Bob Ewell] wasn't crazy, mean as hell. Low-down skunk with enough liquor in him to make him brave enough to kill children. He'd never have met you face to face."
__[ATTICUS] "...I can't conceive of a man who'd—"
__[SHERIFF TATE] "Mr. Finch, there's just some kind of men you have to shoot before you can say hidy to ‘em. Even then, they ain't worth the bullet it takes to shoot 'em. Ewell ‘as one of 'em."
__[ATTICUS] "...I thought he got it all out of him the day he threatened me. Even if he hadn't, I thought he'd come after me."
__[SHERIFF TATE] "He had guts enough to pester a poor col_ored woman, he had guts enough to pester Judge Taylor when he thought the house was empty, so do you think he'da met you to your face in daylight?"
CHAPTER 30 -- Sheriff Tate gives his expert opinion of Bob Ewell.
__[Sheriff Tate] "I'm not a very good man, sir, but I am sheriff of Maycomb County. Lived in this town all my life an‘ I'm goin' on forty-three years old. Know everything that's happened here since before I was born. There's a b_lack boy dead [Tom Robinson] for no reason, and the man [Bob Ewell] responsible for it's dead. Let the dead bury the dead this time, Mr. Finch. Let the dead bury the dead."
Does it have to be from him, or can it be from other characters showing that he's a horrible character?
SLW22: Thank you for selecting my answer as the "Best Answer." I know the book well, and I regard it as amongst the classics of 20th Century American literature. I am pleased that my answer proved helpful to you. I appreciate your comment and the five star rating.