Ma Xiguang (traditional Chinese: 馬希廣; simplified Chinese: 马希广; pinyin: Mǎ Xīguǎng; died 25 January 951), courtesy name Depi (德丕), was the fourth ruler of the Chinese Ma Chu dynasty during the Five Dynasties and Ten Kingdoms period.

It is not known when Ma Xiguang was born. He was Chu's founder Ma Yin (King Wumu)'s 35th son, and was the full younger brother of his fourth son Ma Xifan, both born of his concubine Lady Chen. As Ma Yin, at the time of his death in 930, ordered that his sons succeed each other based on age, Ma Xifan succeeded their older brother Ma Xisheng in 932 upon Ma Xisheng's death. During Ma Xifan's reign, Ma Xiguang, who was said to be careful and obedient in his disposition, was particularly beloved by Ma Xifan.

As of 947, Ma Xiguang carried the titles of deputy military governor of Chu's capital circuit Wu'an (武安, headquartered at Chu's capital Changsha) (with Ma Xifan himself being the military governor (Jiedushi), army commander of the Tiance Headquarters (as Ma Xifan was the Tiance Grand General (天策上將軍)), and military governor of Zhennan Circuit (鎮南, headquartered in modern Nanchang, Jiangxi — an honorary title as Zhennan was then the possession of Chu's northeastern neighbor Southern Tang). Ma Xifan had him oversee the headquarters matters. When Ma Xifan died suddenly in 947 without designating an heir, his staff members discussed who should be invited to succeed him. The officers Zhang Shaodi (張少敵) and Yuan Yougong (袁友恭) argued that Ma Yin's 30th son Ma Xi'e, who was then serving as the military governor of Wuping Circuit (武平, headquartered in modern Changde, Hunan) and acting prefect of Yong Prefecture (永州, in modern Yongzhou, Hunan), and who was the oldest surviving son of Ma Yin's, should be invited to succeed. The officers Liu Yantao (劉彥瑫) and Yang Di (楊滌) and the officials Li Honggao (李弘皋) and Deng Yiwen (鄧懿文) wanted to support Ma Xiguang. Zhang stated, "Yong Prefecture is older and is strong-willed, and will surely not willingly serve under the Commander. If we are to support the Commander, we must think of a careful strategy to control Yong Prefecture such that he will not move against the Commander. Otherwise, the state will be endangered." The senior official Tuoba Heng (拓拔恆) also stated, "Even though Master 35 governs the matters of the headquarters, Master 30 is older. Master 35 should send an emissary to offer to yield. Otherwise, a dispute will surely result." However, Liu and his partisans stated, "Today, the governance is in your hands. If you refuse what Heaven gives to you and let someone else take it, where will we be in the future?" Ma Xiguang, who was weak-willed and not sure what to do, allowed Liu and the others to announce that it was Ma Xifan's will that he succeed to the throne. Zhang, knowing that disaster was coming, claimed illness and withdrew from headquarters, as did Tuoba.

In fall 947, Liu Zhiyuan the emperor of Later Han, who had just recently taken over the Central Plains, bestowed on Ma Xiguang (whose Chu state was traditionally a vassal of the Central Plains states) the titles of Tiance Grand General, military governor of Wu'an, overall commander of the circuits south of the Yangtze River, Zhongshu Ling (中書令), and Prince of Chu.

Meanwhile, Ma Xiguang's younger half-brother Ma Xichong, who was a full brother to Ma Xi'e, had been writing secret letters to Ma Xi'e, inciting him by arguing that Liu Yantao and the others had gone against Ma Yin's instructions. When Ma Xi'e was approaching Changsha from Yong in order to mourn Ma Xifan, Ma Xiguang, at Liu's suggestion, sent the guard commander Zhou Tinghui (周廷誨) with a fleet to intercept him at Dieshi (跌石), where he ordered the Yong soldiers to be disarmed before they would be allowed to approach Changsha further. He housed Ma Xi'e at Bixiang Palace (碧湘宮) and had Ma Xi'e mourn there, not allowing him to go to Ma Xiguang's palace to meet with Ma Xiguang. After mourning, Ma Xi'e requested permission to return to Wuping's capital Lang Prefecture (朗州). Zhou suggested to Ma Xiguang that he kill Ma Xi'e, but Ma Xiguang responded, "How would I have the heart to kill my older brother? I would rather divide Tan (潭州, i.e., Changsha) and Lang and govern them separately." He gave Ma Xi'e many gifts and allowed him to return to Lang. However, Ma Xichong continued to spy on Ma Xiguang and enticed Ma Xi'e to rebel, offering to assist him if he did.

In fall 948, Liu Sheng, the emperor of Chu's southern neighbor Southern Han, sent his official Zhong Yunzhang (鍾允章) as an emissary to Chu, asking that the states enter a marriage. (The states had previously entered such a marriage, as Liu Sheng's father Liu Yan had married Ma Xiguang's Empress Ma as his empress.) Ma Xiguang refused. This angered Liu Sheng, who then asked Zhong for his impressions about Chu, "Is Lord Ma capable of managing a campaign to the south?" Zhong responded, "The Ma brothers are busy with their infighting. How would they be able to damage us?" Liu Sheng, pleased, stated, "True. Ma Xiguang is cowardly and miserly, and his soldiers have long forgotten about war. This is the time for me to advance." Late in the year, Liu Sheng sent the eunuch general Wu Huai'en (吳懷恩) to attack Chu, and captured He (賀州, in modern Hezhou, Guangxi) and Zhao (昭州, in modern Guilin, Guangxi) Prefectures.

Meanwhile, Ma Xi'e submitted a petition to then-Later Han emperor Liu Chengyou (Liu Zhiyuan's son and successor) that he be allowed to separately submit tributes to the emperor and requested a commission separate from Ma Xiguang (in essence, asking that the Chu state be divided formally). Ma Xiguang, under advice by his guard officer Ou Honglian (歐弘練) and liaison to the Later Han court Zhang Zhongxun (張仲荀), sent many gifts to the high-level officials that Liu Zhiyuan left in charge of Liu Chengyou's administration, asking them to reject Ma Xi'e's proposal. As a result, Liu Chengyou issued an edict to both Ma Xi'e and Ma Xiguang, stating, "Brothers should have harmony. Whatever Ma Xi'e wants to submit should be submitted under Ma Xiguang's." Ma Xi'e was displeased.

In 949, Ma Xi'e openly rose against Ma Xiguang. He mobilized the men of Lang and built 700 ships, intending to attack Tan, despite his wife Lady Yuan's urging against such action. When Ma Xiguang heard of this, he initially wanted to capitulate, stating, "Lang Prefecture is my older brother. I should not fight with him, and I shall yield the kingdom to him." Liu Yantao and Li Honggao urged him against doing so. He thereafter sent Wang Yun (王贇) the prefect of Yue Prefecture (岳州, in modern Yueyang, Hunan) to command an army against Ma Xi'e, with Liu serving as Wang's army monitor. Wang was able to defeat Ma Xi'e and capture 300 of Ma Xi'e's ships. Wang chased Ma Xi'e and came close to capturing him, but Ma Xiguang recalled his army, stating to him, "Do not harm my brother." When Ma Xi'e fled back to Lang, Lady Yuan, stating, "Disaster is coming, and I do not wish to see it," committed suicide by jumping into a well, but that did not stop Ma Xi'e's subsequent machinations. Shortly after, when the Later Han general Guo Wei suppressed the rebellion of the general Li Shouzhen, the Later Han government decided to reward many vassals with honorary titles, and Ma Xiguang received the title of Taiwei (太尉, one of the Three Excellencies). Meanwhile, Ma Xiguang's younger brother Ma Xizhan (馬希瞻) the military governor of Jingjiang Circuit (靜江, headquartered in modern Guilin), had been sending emissaries to both Ma Xi'e and Ma Xiguang, hoping to stop their wars, but neither listened to him. In fear that this would lead to the Ma clan's destruction, Ma Xizhan developed ulcers on his back and died.