There are many Buddhist mantras, these are some well known ones.
Om Mani Padme Hum
Om Mani Padme Hum is a well known Tibetan Buddhist mantra.
The Dalai Lama says,
"It is very good to recite the mantra Om mani padme hum, but while you are doing it, you should be thinking on its meaning, for the meaning of the six syllables is great and vast...
The first, Om [...] symbolizes the practitioner's impure body, speech, and mind; it also symbolizes the pure exalted body, speech, and mind of a Buddha[...]"
"The path is indicated by the next four syllables. Mani, meaning jewel, symbolizes the factors of method: (the) altruistic intention to become enlightened, compassion, and love.[...]"
"The two syllables, padme, meaning lotus, symbolize wisdom[...]"
"Purity must be achieved by an indivisible unity of method and wisdom, symbolized by the final syllable hum, which indicates indivisibility[...]"
"Thus the six syllables, om mani padme hum, mean that in dependence on the practice of a path which is an indivisible union of method and wisdom, you can transform your impure body, speech, and mind into the pure exalted body, speech, and mind of a Buddha[...]"
- Tenzin Gyatso, 14th Dalai Lama, "Om Mani Padme Hum"
Green Tara MantraOm Tare Tuttare Ture Soha
An Invocation to Tara, the female counterpart of Avalokiteshvara, the Bodhisattva of Compassion. Tara is pictured as many-armed, symbolizing the powers and attributes she has cultivated to save all sentient beings.
"Om" is the body, speech, and mind of the Buddha.
"Tare" is Dharma, which liberates beings from sufferings.
"Tuttare" is the one that liberates beings from danger.
"Ture" is the one that release beings from sickness.
"Soha" is laying the foundation.
White Tara MantraOm Tare Tuttare Ture Mama
Ayuh Punya Jñana Pustim Kuru Svaha
White Tara is especially associated with compassion, health, healing and longevity.
"mama" is mine, means that I would like to possess the following qualities:
"ayuh" is long life
"punya" is merit that comes from living life in an ethical way. (In the Tibetan version - "pune")
"jnana" is wisdom (Tibetan - "gyana")
"pustim" is increase (Tibetan version - "puntin")
"kuru" is do so, do it now.
"svaha" is hail, or may blessings be upon you (Tibetan version - "soha")
Medicine Buddha MantraTayatha Om Bekandze
Bekandze Maha Bekandze
Radze Samudgate Soha
"May the many sentient beings who are sick, quickly be freed from sickness.
And may all the sicknesses of beings never arise again."
Nam Myoho Renge KyoNam Myoho Renge Kyo
"I devote myself to the Lotus Sutra of the Wonderful Law."
The Lotus Sutra is one of the most important Buddhist scriptures. This mantra evokes the message of this sutra and commits one to follow its teaching.
Gate Gate ParagateOm gate gate paragate
parasamgate bodhi svaha
This mantra was originally derived from the Heart Sutra.
"Gone, gone, gone beyond,
gone altogether beyond,
O what an awakening,
Vajra Guru Mantra
Om Ah Hung
(Mantra of Padmasambhava)
Vajra Guru Padma Siddhi Hung
Padmasambhava was a teacher who is said to have converted Tibet to Buddhism.
"Öm Ah Hung" means the essence of enlightened body, speech, and mind" "Vajra" means thunderbolt or diamond. Energy that can cut through.
"Guru" means wise teacher
"Padma" means lotus/wisdom.
"Siddhi" means supernatural powers and supreme accomplishments
"Hung" means right now!