Other Systems
Before Pinyin, a number of different systems for romanizing Chinese were in use. Wade-Giles was developed by two British scholars at Cambridge in the second half of the 19th century and was the system most widely used before Pinyin came into use. Yale was developed in the 1940s for use in teaching Chinese at Yale University and was widely used in teaching, but was also eventually supplanted by Pinyin. The existence of these other systems is why Chinese people often spell their names in English differently than they do in pinyin. For example, many people whose surname is 张 zhāng spell their name Chang.
In addition, there is a system widely used in Taiwan called 主音符号 zhǔ yīn fú hào that does not use roman letters, but instead symbols developed specifically for this purpose. The advantage to using that system for a foreign learner is that there is no confusion with the pronunciation of the letters in English. Even in Taiwan however, many textbooks now list both Zhuyin Fuhao and Pinyin.
There was also a system called Gwoyeu Romatzyh 国语罗马字 which was developed specifically to address the difficulty foreign learners of Chinese have with tones. Rather than representing the tones with a number or a mark, every syllable has four slightly different ways of writing it, based on the tone.
See the comparison table here.