| Letter-shaped bolt fastener | 27 |
| Letter-shaped bit of NASA equipment | 35 |
| Letter-shaped bike lock | 23 |
| Letter-shaped beam | 18 |
| Letter-shaped bar | 17 |
| Letter-shaped aperture | 22 |
| Letter-shaped annex | 19 |
| Letter-routing number | 21 |
| Letter-routing letters | 22 |
| Letter-routing abbr. | 20 |
| Letter-reading rituals | 22 |
| Letter-perfect time | 19 |
| Letter-perfect school event | 27 |
| Letter-perfect contest? | 23 |
| Letter-perfect | 14 |
| Letter-opening word | 19 |
| Letter-opener, at times | 23 |
| Letter-opener for some | 22 |
| Letter-making machine | 21 |
| Letter-getting opportunities | 28 |
| Letter-getter, for short | 24 |
| Letter-forming dance | 20 |
| Letter-extending abbr. | 22 |
| Letter-exchanging friends | 25 |
| Letter-ending words | 19 |
| Letter-ending word | 18 |
| Letter-ending abbr. | 19 |
| Letter-drop site: abbr. | 23 |
| Letter-closing words | 20 |
| Letter-closing word | 19 |
| Letter-box inscription | 22 |
| Letter-bottom letters | 21 |
| Letter-bottom abbr. | 19 |
| Letter, of sorts | 16 |
| Letter, in Soho | 15 |
| Letter, in Madrid | 17 |
| Letter's sign | 17 |
| Letter's rest period? | 25 |
| Letter's paper | 18 |
| Letter's number | 19 |
| Letter's need | 17 |
| Letter's must-have | 22 |
| Letter's first word | 23 |
| Letter's end? | 17 |
| Letter's cousin | 19 |
| Letter's attachment (Abbr.) | 31 |
| Letter's antecedent | 23 |
| Letter you can read without the light on | 40 |
| Letter Y sporter | 16 |
| Letter X? | 9 |
| Letter written as a straight vertical line | 42 |
| Letter writing: Abbr. | 21 |
| Letter writing, some would say | 30 |
| Letter writing, some say | 24 |
| Letter writing, it's said | 29 |
| Letter writing, as some would say | 33 |
| Letter writing and blacksmithing | 32 |
| Letter writer? | 14 |
| Letter writer, formally | 23 |
| Letter writer's signoff | 27 |
| Letter writer's sign-off | 28 |
| Letter writer's embellishment | 33 |
| Letter writer's aid | 23 |
| Letter writer's afterthoughts | 33 |
| Letter writer's 52? | 23 |
| Letter writer | 13 |
| Letter with the largest section in a dictionary | 47 |
| Letter with jay or tee | 22 |
| Letter with a right angle | 25 |
| Letter with a limited amount of space | 37 |
| Letter with a double twist | 26 |
| Letter with a double curve | 26 |
| Letter with a 90-degree bend | 28 |
| Letter winner | 13 |
| Letter wearers, e.g. | 20 |
| Letter wearer: Abbr. | 20 |
| Letter voiced by a Greek giant? | 31 |
| Letter vendor? | 14 |
| Letter used with theta and phi to represent spherical coordinates | 65 |
| Letter used to represent resistance | 35 |
| Letter used to represent Lagrange multipliers | 45 |
| Letter used as a density symbol | 31 |
| Letter upon which this puzzle's theme is built | 50 |
| Letter two before iota | 22 |
| Letter turner | 13 |
| Letter trio | 11 |
| Letter train | 12 |
| Letter toppers | 14 |
| Letter to the editor that might be received immediately | 55 |
| Letter to Santa, essentially | 28 |
| Letter to Santa, e.g. | 21 |
| Letter to Santa contents | 24 |
| Letter to Odin? | 15 |
| Letter to a Viking? | 19 |
| Letter to a Viking | 18 |
| Letter thought to resemble a skull | 34 |
| Letter that, as it appears in the middle of this grid, can precede the first words of the starred entries | 105 |
| Letter that's opened with a double-click | 44 |
| Letter that's not really at the end of the Greek alphabet | 61 |
| Letter that's also a name | 29 |