Upaka the Ajivaka
Upaka the Ajivaka, according to the Ariyapariyesana Sutta, is the first person Buddha met after he became enlightened.
Within the Ariyapariyesana Sutta, the Buddha says:
Then, having stayed at Uruvela as long as I liked, I set out to wander by stages to Varanasi. Upaka the Ajivaka saw me on the road between Gaya and the (place of) Awakening, and on seeing me said to me, 'Clear, my friend, are your faculties. Pure your complexion, and bright. On whose account have you gone forth? Who is your teacher? In whose Dhamma do you delight?'
When this was said, I replied to Upaka the Ajivaka in verses:
all-knowing am I,
with regard to all things,
released in the ending of craving:
having fully known on my own,
to whom should I point as my teacher? 
I have no teacher,
and one like me can't be found.
In the world with its devas,
I have no counterpart.
For I am an arahant in the world;
I, the unexcelled teacher.
I, alone, am rightly self-awakened.
Cooled am I, unbound.
To set rolling the wheel of Dhamma
I go to the city of Kasi.
In a world become blind,
I beat the drum of the Deathless.'
'From your claims, my friend, you must be an infinite conqueror.'
'Conquerors are those like me
who have reached fermentations' end.
I've conquered evil qualities,
and so, Upaka, I'm a conqueror.'
When this was said, Upaka said, 'May it be so, my friend,' and — shaking his head, taking a side-road — he left.
We hear that after this meeting Upaka went to the Vaŋkahāra country and there, having been attended to by a certain Cāpā, a hunter's daughter, fell in love with her and married her. Thereafter he made his living selling the meat the hunter killed.
This Cāpā, who had aparently admired Upaka as long as he had been an ascetic, began to dispise him for having been entrapped by her and endlessly ridiculed him to the end that he left her and making his way to Savatthi, he found the Buddha and entered the order. It was said he became an Anagamin and being reborn in the Aviha Realm reached Arahantship there almost immediately. Cāpā too, apparently joined the order and became an Arahant.
Her life story has a slightly different version of Upaka's meeting with the Buddha. It ends:
The ascetic, discerning the omniscience and great mission of the Master, was comforted in mind, and replied:
'Friend, may these things be! Thou art worthy to be a conqueror, world without end!'
Then, taking a by-road, he came to the Vankahara country, and abode near the hamlet of the trappers, where the head trapper supplied his wants.
- The Noble Search: Ariyapariyesana Sutta (MN 26), Dhammatalks.org