- Letter sent through cyberspace
- Letter sequence
- Letter sequence that symbolizes easiness
- Letter series
- Letter shaped like a horseshoe
- Letter shaped like a P
- Letter shaped like an upside-down U
- Letter shuffle
- Letter shuffles
- Letter sign-off
- Letter signoff
- Letter similar to a German Eszett
- Letter sound
- Letter spelled by inserting a letter into another letter
- Letter start
- Letter starter
- Letter starter of yore
- Letter stick-on
- Letter string
- Letter stroke
- Letter strokes
- Letter successor, to a large degree
- letter such as m or n
- letter such as n or m
- letter Sweater
- Letter switched to ess in this puzzle's theme
- Letter taker
- Letter taker, for short
- Letter takers, for short
- Letter than rhymes with the ones just before and after it
- Letter that appears at least once in every single answer in this puzzle
- Letter that appears twice in the Schrödinger equation
- Letter that bends 90 degrees
- Letter that can have a cedilla in French
- Letter that comes before upsilon
- Letter that doesn't need a stamp
- Letter that doesn't need an envelope or stamp
- Letter that follows epsilon
- Letter that follows pi
- Letter that forms a right angle
- Letter that hints at how 18 answers in this puzzle should be filled in
- Letter that looks like a pitchfork
- letter that looks like a slingshot 2wds
- Letter that may be used by 61-Down
- Letter that might go through a filter
- Letter that might include an emoticon
- Letter that opens with a click
- Letter that requires clicking, not licking
- Letter that requires no postage
- Letter that resembles the "y" of Disney's signature
- Letter that rhymes with "theta"
- Letter that rhymes with 34-Across and 21-Down
- Letter that rhymes with its preceding and following letter
- Letter that rhymes with its two successors
- Letter that rhymes with three other letters
- Letter that rhymes with three others
- Letter that some feel should have its own day, rather than pi having Pi Day
- Letter that sounds like a question
- Letter that sounds like a swath of seats
- Letter that sounds like an expression of relief
- Letter that, surprisingly, is not the end of the Greek alphabet
- Letter that's also a name
- Letter that's an anagram of 111-Down
- Letter that's an anagram of 16-Across
- Letter that's not really at the end of the Greek alphabet
- Letter that's opened with a double-click
- Letter thought to resemble a skull
- Letter through a filter
- Letter to a Viking?
- Letter to cross
- Letter to Liverpudlians
- Letter to Odin?
- Letter to Santa
- Letter to the ___
- Letter to the editor that might be received immediately
- Letter to the editor, often
- Letter to Yanni?
- letter toppers
- Letter train
- Letter trio
- Letter two after tau
- Letter two before iota
- Letter two before tau
- Letter upon which this puzzle's theme is built
- Letter used as a density symbol
- Letter used in Old English and Icelandic
- Letter used to represent resistance
- Letter vendor?
- Letter voiced by a Greek giant?
- Letter wearer: Abbr.
- Letter wearers, e.g.
- Letter widths
- Letter with a 90-degree bend
- Letter with a double curve
- Letter with a double twist
- Letter with a limited amount of space
- Letter with a right angle
- Letter with a silent letter
- LETTER with cost of answer free to sender
- Letter with curves
- Letter with no curves
- Letter with the largest section in a dictionary
- Letter writer, of a sort
- Letter writer?
- Letter writer's afterthoughts
- Letter writer's aid
- Letter writer's embellishment
- Letter writer's signoff
- Letter writing and sentence diagramming, it's said
- Letter writing, for example
- Letter writing, it's said
- Letter writing, some say
- Letter written as a straight vertical line
- Letter X?
- Letter Y sporter
- Letter you can read without the light on
- Letter you don't pronounce in "jeopardy" and "leopard"
- letter Zola Author
- Letter-bottom abbr.
- Letter-bottom letters
- Letter-box inscription
- Letter-cartification words
- Letter-closing word
- Letter-closing words
- Letter-drawing guide
- Letter-ending abbr.
- Letter-ending word
- Letter-erasing key
- Letter-extending abbr.
- Letter-getter, for short
- Letter-getting opportunities
- Letter-handling org.
- Letter-named thoroughfares in Bklyn.
- Letter-opening word
- Letter-perfect
- Letter-perfect contest?
- Letter-perfect school event
- Letter-reading rituals
- Letter-related
- Letter-routing letters
- Letter-routing number
- Letter-shaped add-on
- Letter-shaped annex
- Letter-shaped auto feature
- Letter-shaped bar
- Letter-shaped beam
- Letter-shaped bike lock
- Letter-shaped bit of NASA equipment
- Letter-shaped bolt fastener
- Letter-shaped bolt holder
- Letter-shaped brace
- Letter-shaped bridge support
- Letter-shaped building addition
- Letter-shaped building beam
- Letter-shaped building girders
- Letter-shaped building part
- Letter-shaped building support
- Letter-shaped clamp
- Letter-shaped construction beam
- Letter-shaped construction beams
- Letter-shaped construction component
- Letter-shaped construction piece
- Letter-shaped construction pieces
- Letter-shaped construction support
- Letter-shaped cross
- Letter-shaped dress style
- Letter-shaped extensions
- Letter-shaped fastener
- Letter-shaped fasteners
- Letter-shaped fitting
- Letter-shaped gasket
- Letter-shaped gasket also known as a toric joint
- Letter-shaped girder
- Letter-shaped girders
- Letter-shaped gripper
- Letter-shaped grippers
- Letter-shaped hardware
- Letter-shaped hardware item
- Letter-shaped hardware items
- Letter-shaped iron bar
- Letter-shaped lift
- Letter-shaped metal fastener
- Letter-shaped muscles, for short
- Letter-shaped opening
- Letter-shaped opening for a bolt
- Letter-shaped opening in a machine shop
- Letter-shaped part of a grate
- Letter-shaped part of a sink
- Letter-shaped pipe
- Letter-shaped plumbing fitting
- Letter-shaped plumbing trap
- Letter-shaped shelf support
- Letter-shaped shirt
- Letter-shaped shirt feature
- Letter-shaped shoe band
- Letter-shaped shoe fastener
- Letter-shaped shop devices
- Letter-shaped sink fitting
- Letter-shaped sink pipes
- Letter-shaped skyscraper support
- Letter-shaped steak
- Letter-shaped steel girder
- Letter-shaped structural beam
- Letter-shaped structural piece
- Letter-shaped structural support
- Letter-shaped struts
- Letter-shaped support
- Letter-shaped support piece
- Letter-shaped supporter
- Letter-shaped supports
- Letter-shaped wing
- Letter-shaped wood holder
- Letter-shaped woodworking vise
- Letter-shaped, threaded fastener
- Letter-starting word
- Letter-to-Santa enclosure
- Letter-to-Santa itemization
- Letter-to-Santa word
- Letter-turner for Pat
- Letter-turner of TV
- letter-type
- letter-writer
- Letter-writer's sign-off
- Letter-writers' afterthoughts: Abbr.
- Letter-writing aid
- Letter-writing buddy
- Letter-writing friend
- Letter-writing friend from far away
- Letter-writing guide
- Letter-writing prisoner, perhaps
- LETTER, capital
- Letter, of sorts
- Letter?
- Letter's "To:" line: Abbr.
- Letter's capital?
- Letter's cross stroke
- Letter's end?
- Letter's first word
- Letter's need
- Letter's number
- Letter's paper
- Letter's rest period?
- Letter's sign
- LETTERBOX
- Letterboxing or geocaching, e.g.
- lettered
- Lettered Bklyn. thoroughfare
- Lettered fords
- Lettered man's letters
- LETTERED persons