Giant

The language that giants share is one of the few remnants form their once-grand empire. Over time it has fragmented into many dialects, and each type has its own distinctive accent, but giants of different types can generally understand one another.
Any non-giant who learns the Giant language can converse with all types of giants, but giants sometimes have a hard time hearing the tiny voices of human-sized creatures, and some vowel sounds emitted by giants are nearly impossible to reproduce for any creature that doesn't have lungs as large as beer barrels.
For much of their written communication, giants use a modified version of the runic letterforms claimed by the dwarves as their own. This alphabet is used widely today, including by many traditional enemies of the dwarves such as orcs, giants, and goblinoids. That giants were first in the world and thus the creators of the script is a fact that giants take for granted but that dwarves hotly dispute.