《One》是韩国民谣女歌手李秀英（이지연）演唱的一首歌曲。同时，此曲也是游戏《RF Online》的主题曲。
《RF Online》是一款由韩国CCR公司开发，广东数据通信于2005年12月15日运营的网络游戏。游戏讲述了玩家扮演的三大种族（阿克雷提亚、贝尔托、克拉）之间的反目与对立，以及和神秘病毒斗争的故事。
One歌词：
When I saw you for the first time
I knew you were the one
You didn't say a word to me
But love was in the air
Then you held my hand
Pulled me into your world
From then on my life
Has changed for me
Now I'll never feel lonely again
Coz you are in my life
Love
How can I explain to you
The way I feel inside when I think of you
I thank you for everything that you showed me
Don't you ever forget that I love you
Love I know that someday real soon
You'll be right next to me
Holding me so tight
So I will always be yours
Although we can't be together now
Remember I am here for you
And I know you're there for me
Whenever I want to be with you
I just close my eyes and pretend you're near
I see you I touch you I feel you like real
Nothing can ever change what I feel inside
How long must I be far away from you
I don't know dear but I know we are one
追梦人钢琴谱 张韶涵 你的心需要一束光
爱如潮水钢琴谱 张信哲｜爱如潮水，将我向你推，永不停息
相见恨晚钢琴谱 彭佳慧-你说是我们相见恨晚，我说为爱你不够勇敢
昆明湖钢琴谱 后弦-一个真正的旅游胜地
分手快乐钢琴谱-梁静茹｜让我们鼓起勇气分手快乐
我怀念的钢琴谱 孙燕姿 曾经想要珍惜却最终失去
鼓浪屿之波钢琴谱-张暴默-寄托两岸思念之情
哑巴钢琴谱 薛之谦 我就像一个哑巴一样，你翻译不了我的声响
一丝不挂钢琴谱 陈奕迅-发现沿途寻找的快乐 仍系于你肩膊
夜夜夜夜钢琴谱 齐秦 你也不必牵强再说爱我
Because He Lives钢琴谱-Bill Gloria Gaither
Bad Apple钢琴谱-ZUN
Pied Piper钢琴谱-防弹少年团 BTS
一笑江湖钢琴谱-闻人听书
记忆深处钢琴谱-朴正元
如果能在一起钢琴谱-梁静茹
Suspirium钢琴谱-Thom Yorke
Pink White钢琴谱-Frank Ocean
英雄落幕钢琴谱-燃烧的音符
轻漪的节音钢琴谱-HOYO-MiX
迷宫钢琴谱-七朵花
Benedictus钢琴谱-Karl Jenkins
Everything Stays钢琴谱-Rebecca Sugar
Green Hill Zone钢琴谱-中村正人
I Like You So Much Youll Know It钢琴谱-Ysabelle Cuevas