And baleful, as in full of threat, ill-omens, and foreboding. Which suggests yet another meaining for “bale” itself.
So,
baleful: dire, wicked, cruel
baneful: deadly
mask: a covering for the face
masque: a type of histrionic entertainment; a masquerade
fairy: land or home of the fays; a type of supernatural being
peri: a more Persian type of superhuman being or sprite
Perry - a cider made from pears instead of apples.
Ferry: a boat that carries people and/or vehicles back and forth between two or more ports.
Peri peri: A type of hot pepper.
Contemptuous: expressive of contempt
Contemptible: deserving contempt
(I’m sure I’ve come across similar pairs of adjectives that get confused with each other, but no other examples come to mind immediately) I
Bertie Wooster and Jeeves say: 
incredulous: unbelieving, skeptical, lacking credulity
incredible: unbelievable, implausible, lacking credibility
Nauseated (of a person) feeling sick to one’s stomach, as if about to vomit
Nauseous (of an object or event) causing a person to feel nausea
This is the traditional distinction, but in modern usage, especially in US English, “nauseous” is often used as a synonym for “nauseated”. Most dictionaries accept this change, although some prescriptive style guides still advise against using “nauseous” to mean “nauseated” and claim that a sentence like “I feel nauseous” is erroneous (unless you mean that you feel that you’re causing someone else to feel nausea).
Just heard another confusion (in an episode of Foyle’s War no less, I’d have thought Anthony Horowitz - and the character he wrote the line for - knew better):
Benefactors: people who do good for others
Beneficiaries: people who benefit from what their benefactors do.
People who can’t distinguish between entomology and etymology bug me in ways I cannot put into words.
LOL! 
pimple: a small skin infection.
pimpernel: a type of flower.
When I saw the book The Scarlet Pimpernel I wondered why anyone would read a whole book about a pimple.
You are S. Baldrick and I claim my five pounds.
or a pimp.
gorilla: largest of the apes
guerrilla: small independent military troop
peak: the highest point of something (e.g., a mountain or an achievement)
peek: a glimpse of something, usually sought out, and often somewhat furtively
peke: abbreviated name for Pekingese dogs
Pique: to stimulate (appetite, interest, or curiosity).
So if you get a glimpse of an interesting looking dog on a mountain top, can you say that the peek at the peke on the peak piqued your interest?